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JOURNAL OF THE
SOCIETY OF

MOTION PICTURE

AND

TELEVISION

ENGINEERS

THIS ISSUE IN TWO PARTS
Part I, December 1952 Journal • Part II, Index to Vol. 59

VOLUME 59
July — December 1952

SOCIETY OF MOTION PICTURE
AND TELEVISION ENGINEERS

40 West 40th St., New York 18

CONTENTS— Journal

Society of Motion Picture and Television Engineers

Volume 59 : July — December 1952

Listed below are only the papers and major reports from the six issues. See the
Volume Index for those items which generally appear on the last few pages of each
issue: Standards, Society announcements (awards, Board meetings, committee
reports, conventions, engineering activities, membership, nominations, section
activities), book reviews, current literature, letters to the Editor, new products and
obituaries.

Dual-Purpose Optical Sound Prints

C. E. BEAGHELL and G. G. GRAHAM 1

Theory of Parallax Barriers SAM H. KAPLAN 1 1

New Direct- Vision Stereo-Projection Screen

VV. WHEELER JENNINGS and PIERRE VANET 22

Automatic Torque Controller for Torque Motors . . CARL E. KITTLE 28
Three-Phase Power From Single- Phase Source . . . A. L. HOLCOMB 32
Continuous Arc Projector Light Meter . . . HARRY P. BRUEGGEMANN 40
Use of a Rotating-Drum Camera for Recording Impact Loading De-
formation D. F. MUSTER and E. G. VOLTERRA 44

The Navy's Training Film Production Program

W. R. CRONENWETT and W. M. TIMMONS 49

Nonsilver Photographic Processes THOMAS T. HILL 58

August

Optimum Exposure of Sound Tracks on Kodachrome Films ....

ROBERT C. LOVICK 81

Densitometry of Silver Sulfide Sound Tracks . . ROBERT C. LOVICK 89

Modulated Air Blast for Reducing Film Buckle . . . WILLY BORBERG 94
A Method of Direct-Positive Variable-Density Recording With the

Light Valve O. L. DUPY 101

ii Contents: Journal of the SMPTE Vol. 59

International Auxiliary Language for Motion Pictures . . MARY BRAY 107
Un commercial phonoregistrator binaural — Interlingua Translation

of First Page of "A Commercial Binaural Recorder"

ALEXANDER CODE 108

A Commercial Binaural Recorder OTTO C. BIXLER 109

Follow-Focus Device and Camera Blimp for 16mm Professional

Camera .... LEE R. RICHARDSON and WILLIAM N. GAISFORD 118

Instantaneous Theater Projection Television System

VICTOR TRAD and RICARDO MUNIZ 125
Theater Television Progress NATHAN L. HALPERN 140

September

SMPTE Engineering Activities FRED T. BOWDITCH 161

Explosive Argon Flashlamp

C. H. WINNING and HAROLD E. EDGERTON 178
Integrating-Type Color Densitometer .... FRANK P. HERRNFELD 184

Transmission Color in Camera Lenses PHILIP T. SCHARF 191

Cameo Film Production Technique

CHARLES F. HOBAN and JAMES A. MOSES 195

Auditorium Specifically Designed for Technical Meetings

D. MAX BEARD and A. M. ERICKSON 205
Safety Requirements in Projection Rooms and Television Studios . .

SAMUEL R. TODD 212

Military-Type Lenses for 35mm Motion Picture Cameras

PAUL C. FOOTE and R. E. MIESSE 219
October

Basic Principles of the Three-Dimensional Film

RAYMOND SPOTTISWOODE, N. L. SPOTTISWOODE and CHARLES SMITH 249

(for three errata, see Dec. p. 516)
Drawing in Three Dimensions for Animation and Stereoscopic

Processes ERNEST F. HISER 287

Animation for Individual Television Stations . . . ERNEST F. HISER 293
X-ray Motion Picture Techniques Employed in Medical Diagnosis and

Research . S. A. WEINBERG, J. S. WATSON, JR., and G. H. RAMSEY 300

Appendix: A New Kodak //0.75 Fluro Ektar Lens

W. E. SCHADE 307
A Precision Color Temperature Meter for Tungsten Illumination . .

G. H. DAWSON, D. E. GRANT and H. F. OTT 309

Comparison of Recording Processes (Reprint) . . JOHN G. FRAYNE 313
A Building-Block Approach to Magnetic Recording Equipment Design

KURT SINGER and J. L. PETTUS 319
A-C High-Intensity Arc Slide Projector ARTHUR J. HATCH 335

Contents: Journal of the SMPTE Vol. 59 iii

November

The Economics of High-Speed Photography .... A. C, KELLER
Transient Pressure Recording With a High-Speed Interferometer

Camera WILLARD E. BUCK

Optimum Slit Height in Photographic Sound-Track Reproducers .

W. K. GRIM WOOD and J. R. HORAK
Dual Photomagnetic Intermediate Studio Recording

JOHN G. FRAYNE and JOHN P. LIVADARY

Television Facilities of the Canadian Broadcasting Corp. . J. E. HAYES
Use of Ansco Color Film in Commercial Production . REID H. RAY
A Fast-Acting Exposure Control System for Color Motion Picture

Prating JOHN G. STREIFFERT

Motion Picture Studio Lighting Report JOHN W. BOYLE

Film Dimensions Committee Report E. K. CARVER

Optics Committee Report RUDOLF KINGSLAKE

December

The Electronic Camera in Film-Making

NORMAN COLLINS and T. C. MACNAMARA 445

Signal Corps Mobile Television System JOHN S. AULD 462

Motion Photography for Combustion Research . . F. W. BOWDITCH 472
Accuracy Limitations on High-Speed Metric Photograph)

AMY E. GRIFFIN and ELMER E. GREEN 485
High-Speed Cine-Electrocardiography .... JOSHUA J. FIELDS,

Louis FIELDS, ELEANOR GERLACH and MYRON PRINZMETAL 493

Optical Aids for High-Speed Photography

DAVID C. GILKESON and A. EUGENE TURULA 498

A High-Speed Rotating-Mirror Frame Camera . . BERLYN BRIXNER 503
Acoustic Problems at the "Waldbiihne" Open-Air Sound Theater in

Berlin HANS SIMON 512

Some Geometrical Conditions for Depth Effect in Motion Pictures

EUGENE MILLET 517
Screen Brightness Committee Report . W. W. LOZIER 524

Contents: Journal of the SMPTE Vol.59

Dual-Purpose
Optical Sound Prints

By C. E. BEACHELL and G. G. GRAHAM

This paper describes a method of recording and printing two separate sound
tracks within the normal single-track area for 16mm or 35mm release prints.
A projector conversion kit for reproducing the double tracks separately or
simultaneously is also discussed. This technique has possible application in
reducing distribution costs on foreign versions and in the educational and
television fields.

N VIEW OF the greatly increased use
of films in the fields of government,
education, television and industry, it is
often desirable to have available alternate
sound versions of certain productions in
order to serve the widest possible
audience.

Typical applications of these versions
are:

(a) For distribution in foreign coun-
tries.

(b) For presentation to audiences of
different intellectual interests and train-
ing. For example, a drug firm may
wish to present one technical version of
a treatment to a medical audience and,
using the same visuals, also present a lay
audience version.

Presented on April 25, 1952, at the Society's
Convention at Chicago, 111., by C. E.
Beachell and G. G. Graham, National
Film Board of Canada, John St., Ottawa,
Ontario, Canada.

the music track because of trade regula-
tions.

Because of these and other potential
needs it is now common practice for
many film production units to record,
in addition to the original language
version of the film, a separate music and
effects track and a voice and effects
track. The music and effects track
may be used for foreign or other English
language dubbing and the voice and
effects track may be used for television
prints where restrictions on the musical
score are in effect.

The details of preparing an alternate
sound version of a completed production
vary somewhat in different studios, but
in general they follow this pattern.

First consideration must be given to
the economic factors of distribution
which in turn will indicate the most
desirable method of presenting the new-
sound treatment of the film to the public.
With an eye to the budget, the producer
and distributor will probably discuss
these techniques:

July 1952 Journal of the SMPTE Vol. 59

(a) The sound volume on the pro-
jector may be turned down and a com-
mentary may then be supplied by the
operator. This method is often used
in schools with reasonable effectiveness
but in the hands of an inexperienced
person the results can be disastrous.

(b) Subtitles may be added to existing
prints, which have completed domestic
distribution, by means of an etching
process. If additional prints are re-
quired, subtitles may be printed from
mattes. Choice of either of these
methods depends upon the volume of
prints required.

(c) For prestige purposes and/or com-
mercial distribution completely new
sound tracks may be prepared which
will permit the film to be presented as a
standard composite print. Current de-
velopments in magnetic striping of
existing and new prints suggests a further
method of presenting this type of version.

Perhaps it is in order to discuss
methods (b) and (c) more fully.

Etched Subtitles

In this process, subtitles giving the
essential text required to explain the
action of the visuals are added to the
lower one-third to one-quarter of several
frames of each scene by means of these
steps:

(a) The print embossing plates which
provide a relief image of the text type
are made. One European process per-
mits direct typing on the film and thus
obviates the need of individual type
plates.

(b) The print to be subtitled is
coated with a bleach-resistant material
such as paraffin wax.

(c) At the desired places throughout
each reel the printing plate is hot-
pressed on the coated film so that the
type image penetrates to the emulsion
surface.

(d) The film is then run through a
bleach and clearing bath during which
the image in the type areas is completely
removed.

(e) The wax coating is removed with
suitable solvent and the subtitles appear
on the completed print as white letters.

Matte Printed Subtitles

In this process a text similar to that
described above is applied during the
release printing operations as follows:

(a) Individual title cards bearing the
text for each scene are prepared and shot
on the animation stand. If more than
one set of mattes is required, black letters
on a white background may be used to
provide a printing negative.

(b) The negative titles are now
printed on positive stock to provide
black letters against a clear base.

(c) The subtitle printing matte is
synchronized with the release printing
picture negative and both of these films
are run through the printer in contact
with the positive raw stock. The text
appears as white letters against the
picture background.

This is a deliberate simplification of
the preceding process which involves
much more consideration of negative
and positive print densities in the
subtitle areas than is indicated here.

Dubbing

Most of the foreign language dubbing
is presently done in Europe where con-
siderable skills in translating and re-
cording lip-synchronized dialogue have
been developed over many years. The
advantages of this arrangement are:

(a) Translations may be obtained
which contain the current idioms of
the area in question and which avoid
offensive reference to controversial ques-
tions involving the national, political or
religious beliefs of the country concerned.

(b) A relatively large number of
translators and actors are available who
have a detailed knowledge of the English
language and who are trained to inject
the proper feeling and authenticity into
the characterizations.

July 1952 Journal of the SMPTE Vol. 59

this fact, coupled with restrictions on the
import of prints from hard-currency
areas, makes this method of operation
desirable from an economic standpoint.

Recent developments of magnetic
striping, such as those described at this
Society's conventions and in the Journal,
have opened up further possibilities for
the application of alternate sound tracks
to existing prints. The high quality of
reproduction obtained with this system
along with the simplicity of operation
should permit its use in the foreign or
alternate English version field in a most
practical manner.

Obviously the application of a foreign
or alternate English language track to a
commentary-type film is a reasonably
simple operation. It becomes quite
complicated, however, when the sound
must be supplied as dialogue to match
the lip synchronism of the visuals.
Special techniques for analyzing the
voice portions of the original track and
selecting words in the new version
which match the phrasing and inflections
of the original have been developed by
De Lane Lee and others in Europe.
Individual scene loops are recorded on
magnetic stock in an erase-record cycle
until a desirable take is secured. The
individual sequences are later mixed
with the music and effects track (which
has been recorded previously) to provide
the completed track. Usually new tides
are prepared for release printing versions
of this type and with these cut into the
printing dupe and synchronized with
the sound track the film is ready for
release printing. Although this latter
method requires the making of a new
sound track, it is presently considered
to be the most effective way of pre-
senting a supplementary version of a
film. The methods and techniques to
be discussed in this paper deal with the
application and utilization of such
alternate sound tracks.

The National Film Board of Canada
is faced with the continuing problem of
producing films in both the French and

English languages for its domestic dis-
tribution. In addition to this, the
prospect of increased coverage in Europe
to assist the Canadian government's
immigration program as well as greater
activity in the fields of education and
television led to study of methods to
provide greater flexibility in the utiliza-
tion of 16mm and 35mm prints.

The use of subtitles was considered
and abandoned for these reasons:

(a) It is extremely difficult to present
sufficient text within the space allotted
in documentary films where the com-
mentary is not necessarily linked to the
visuals in an obvious manner as is the
case in a story-line type of film.

(b) The attention of the spectator
must be divided between the picture
image and text, and consequently the
ability to understand the film is reduced.

(c) In many areas of the world it is
desirable to show the films to illiterate
audiences which, of course, reduces the
effectiveness of this method.

Magnetic striping provides an ac-
ceptable quality sound track and is ideal
in certain circumstances. Its principal
disadvantages at this time appear to be:

(a) The cost of new projectors or
converting existing projectors is quite
high. This is particularly significant
in areas where several hundred pro-
jectors are in use.

(b) The cost of striping a print and
transferring the new sound track adds
considerably to the sale price of the
print.

(c) The fact that the sound track
can be erased and replaced with an
entirely different track without reference
to the original producer could have
serious consequences. By design or
accident, interpretation of the visuals
could be used indiscriminately to express
opinions which would cause embarrass-
ment to the organization or country
responsible for production and dis-
tribution of the film.

As a result of these conclusions and
to meet the needs of other agencies of

Beachell and Graham: Dual-Purpose Optical Prints

Fig. 1. Close-up of Debrie Sound Adaptor, showing
sound aperture masks in position.

Fig. 2. Normal track provided by Maurer Sound Recorder.
July 1952 Journal of the SMPTE Vol. 59

government concerned with film dis-
tribution the following objectives were
established :

(a) The overall quality of the sound
should not be impaired.

(b) The technique devised must be
applicable to existing films as well as
those to be produced in the future.

(c) In view of the capital investment
in projectors, any method of changing
the character of the sound track must be
accomplished through adaptation of
available equipment. It was, of course,
mandatory that any conversion unit
applied to the projector must not, in
any way, prohibit its use for projection
of standard films.

(d) The technique developed should
insure an appreciable saving in print
costs to the distributor and consumer.

(e) The sound track supplied should
be that prepared by the producer of the
film and should remain a permanent
part of the print itself.

In view of the success achieved in
reproduction of the 50-mil optical track
portion of the striped magnetic sound
systems, it was decided to concentrate
on producing a double optical sound
image each portion of which would be
50 mils in width. Either of these tracks
could then be reproduced at will by
simply inserting a suitable mask in the
sound scanning beam of a 16mm
projector.

In preparing these dual-purpose sound
prints it was found that two methods
could be used. With the use of half-
width masks alternately on opposite
sides of the sound aperture and a double
printing operation, the prints may be
made from existing sound negatives by
the processing laboratory. To avoid the
double-printing operation, a similar
masking technique may be used on an
optical recorder. In this case two
separate recordings are made in the
standard single-track area on an inter-
lock system by exposing one side, then
reversing the mask, rewinding the stock
and exposing the second half.

Adaptation of Printers

For the preliminary experimental work
a double sound head Debrie Matipo
printer was used. The alternate halves
of each sound aperture were masked
with brass shim stock suitably blackened
to reduce reflection (Fig. 1). The
Matipo printer is particularly suitable
for this work since the sound gate is
slightly undercut from the film path.
Consequently a mask may be inserted
in such a manner that it clears the
moving film by about 0.010 in.

To adjust the mask a standard nega-
tive is placed in its normal position on
the aperture. Over this a piece of
positive raw stock is placed so that the
image of the track and the mask im-
pinges on it when illuminated by the
printer lamp. With the use of a tool-
maker's microscope, the mask is moved
to split the track at the 50-mil position.
Fine centering of the mask image on the
positive stock is accomplished by adjust-
ment of the printer-lamp position.
Figure 2 shows a section of multiple
bilateral track from a Maurer recorder.
The track is split in printing half-way
between sections 3 and 4.

Two samples of tracks printed and
recorded in this manner are shown in
Figs. 3 and 4. Figure 3 shows the result
of mask overlap of approximately 0.010
in. which causes a loss of two tracks.
Figure 4 illustrates a finer adjustment of
the masks to eliminate the unexposed
center strip completely.

When it was established that the
unexposed center area could be elimi-
nated, an alternate use of this technique
suggested itself. Instead of putting
entirely different sound tracks on each
50-mil portion, it might now be possible
to print or record different portions of
the same track on each half-track portion.
To check this reasoning a special mix of
a sound track was prepared. The
tracks to be mixed consisted of two
music, and four voice and effects reels.
From the dubbers the sound was fed

Beachell and Graham: Dual-Purpose Optical Prints

Fig. 3. First track split, show-
ing effect of mask overlap.

Fig. 4. Second track split, with masks adjusted to eliminate overlap.

as shown in Fig. 5. The mixer heard
the combined effect of all tracks over
his monitor speakers, but at the record-
ing stage the signals were bridged so
that the music was recorded on an inter-
locked magnetic recorder while the voice
and effects were picked up on a masked
optical system. The magnetic track
was transferred to the opposite half of

the optical negative and the combined
tracks were printed onto the positive
stock. When played on a standard
projector the full track is reproduced,
while on an adapted projector the print
may be played as full sound, voice and
effects, or music only. This type of
print appears to offer certain advantages:
(a) On full-track reproduction, since

July 1952 Journal of the SMPTE Vol. 59

fi/VD FILTtfU

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/•/V OK MIC.

DlfiiOGVB
f*-Z

FP-J

enters B

-
-

MVS/C ft
fP-S

MUSIC B'
F.P-6

MUSIC C~
FP-7

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Fig. 5. Diagram of divided track re-recording system.

the high- and low-frequency components
are physically separated, intermodula-
tion distortion effect in the recording and
printing stages is greatly reduced.

(b) The music portion only of the
track may be reproduced when, for
example, the print is used for educational
purposes and the teacher wishes to
supply his or her own commentary.
Alternatively, many teachers feel that
music detracts from the effectiveness of
an education subject and in such cases
the voice and effects portion alone may
be used.

(c) A third possible application lies
in the television field. Split-track prints
may be distributed generally for re-
production on standard projectors.
However, the same print may be rented
or sold to television stations which in
turn may reproduce only the voice and
effects portion. This eliminates the
need for special prints of sound negatives
where trade regulations prohibit the

reproduction of film music on television
networks.

Mechanical Adaptation of Recorders

Figure 6 shows plan views of the
RCA and Western Electric optical
paths. Suitable half-track masks could
be installed at the points shown. In
the Maurer recorder the mask is intro-
duced at the ultraviolet filter holder
position so that its image is produced
sharply on the film in the desired posi-
tion. During the early experiments
masks were used at the film plane for
reasons of convenience. However, the
points noted in Fig. 6 would permit a
more precise arrangement for con-
tinuous use.

Split-track recording may be used for
two purposes:

(a) To divide the contents of a single
track into two portions: i.e., music,
and voice and effects; or music and
effects, and voice.

Beachell and Graham: Dual-Purpose Optical Prints

DESIRABLE POSITION FOR
HALF-TRACK MASK

Fig. 6. (A) RCA Optical System, plan view; (B) Westrex Optical System, plan view.

(b) To place within the single-track
area of a standard 35mm or 16mm
negative two separate sound versions:
i.e., English and French tracks, two
English tracks, etc.

Where separate language versions are
required, the originals are recorded
separately in the regular manner on
35mm magnetic stock. These tracks
may then be transferred to the masked
recorder as described above.

The particular advantages of double-
track sound negatives are:

(a) The laboratory printing step is
reduced to a standard single operation
and consequently two print versions
may be produced for the price of one.

(b) Any overlap of the masks on the
sound negative record is reproduced as a
continuous black unmodulated line on
the print. This is preferable to the
white line left by overlapping of the
masks on the release printer since this

would raise the noise level when re-
produced on full-width scanning.

(c) On a recorder greater accuracy
of center-line placement can be assured
and the danger of clipping is reduced.
In addition, negative recording stock is
usually in good physical condition so
that no compensation for shrinkage need
be applied.

Projector Conversion

The prototype model shown here
(Fig. 7) is a very simple adaptor which
may be fitted to most 16mm projectors.
The pivoted mask is U-shaped, with
adjusting screws for proper horizontal
positioning of the projector sound
scanning beam. Since the vertical
dimension of the scanning beam is
defined by the optical system of the
projector, no provision need be made for
this on the adaptor. This fortunate
circumstance greatly reduces the manu-

July 1952 Journal of the SMPTE Vol. 59

facturing cost of the unit. With this
adaptor the sound track may be re-
produced as full-width normal, 50-mil
left and 50-mil right. The actual width
of the scanned area is slightly under 50
mils to avoid picking up unwanted
signal due to weave in the film path or
miscentering due to shrinkage. Further
fine adjustment may be made by means
of the adjusting screws if necessary.

The mask is suitably curved so that
it will not cut into the film in the event
of a break or when the end is passing
through.

Using either half of the split track,
the sound quality is quite acceptable.
For experimental purposes an old Bell &
Howell No. 179 projector (Fig. 8) was
selected as representative of a type still

Fig. 7. 16-mm projector adaptor.

Fig. 8. Adaptor in posi- MS
tion on Bell & Howell,
Model 179.

BeacheU and Graham: Dual-Purpose Optical Prints

used extensively in Canada. With the
amplifier in good working condition
and the sound scanning beam balanced
to ±li db across its full width, the
sound level of the half-track is down
approximately 5 to 6 db. The fre-
quency response characteristic remains
unchanged. Signal-to-noise ratio of the
projector is not affected since the scan-
ning beam is mechanically reduced by
one-half. There is an increase of
amplifier noise since the gain must be
increased to compensate for the volume
loss on the half-track. However, this is
not serious for all normal requirements.

While this system is particularly
adaptable to variable density and
multiple bilateral area tracks it is also
applicable to other types of area tracks
with the exception of unilateral records.

In conclusion this 50-mil optical track
system appears to offer the following
advantages which are applicable to
either 35mm or 16mm black-and-white
or color film prints:

(a) Double- and possibly triple-version
tracks may be produced on a single
print at very low cost, thus introducing
economy for film users in various fields.

(b) Using the split tracks for inde-
pendent recording of the low- and high-
frequency components of a single sound
track will reduce intermodulation dis-
tortion. By means of selective playback,
greater utilization of the same print
may be made.

for this purpose will probably be less
than fifteen dollars per machine and the
adaptor will not, in any way, limit the
projector for use with regular films.

Discussion

John G. Frayne: I would like to offer a
suggestion if I may to Mr. Graham. It's
possible with the valve which I believe
you showed in that slide, the RA-1238
push-pull valve, to reconnect it so that
you can record two independent tracks
simultaneously. Have you tried that?

Gerald G. Graham: No, not yet.

Dr. Frayne: It can be done very easily.

Mr. Graham: It's an excellent suggestion.

Dr. Frayne: You merely put the two
separate signals on the two outside noise-
reduction ribbons, superimpose the noise-
reduction currents on these and keep the
center ribbon as a mask. You thus get
two independent tracks. In the case of
variable area, you simply connect each
ribbon to an independent signal and noise-
reduction input and thus obtain two
separate VA tracks.

Mr. Graham: Yes, to date in the experi-
mental work we haven't actually been
delving into the recording system. We've
tried to work outside of that. That is
something we would like to do next.

H. R. Kossman: The speaker mentions
making superimposed titles. However,
there is another method — it's a Debrie
printer which accomplishes this by pro-
jecting one single text frame onto the
negative while the printer runs. This
means a considerable saving in matte
costs.

July 1952 Journal of the SMPTE Vol. 59

Theory of Parallax Barriers

By SAM H. KAPLAN

The parallax barrier, which is a type of selective masking device now being
applied in color television and in stereoscopic imagery, is discussed. A brief
history along with the principle and geometric relationship underlying its
operation is given. Various systems employing two or more image elements
per aperture and utilizing the maximum image area are described. It is
also shown that nonplanar and nonparallel arrangements are possible, and
that plane barrier surfaces may be coupled to nonplanar image surfaces.
Furthermore, lenses may replace the mechanical-type barriers resulting in
a more light-efficient system. Formulae are presented and specific applica-
tions to multiple-color television tubes are discussed.

PARALLAX BARRIER may be defined
as a masking device which, when inter-
posed between an object space and an
image space, prevents any given part
of the image space from being sighted
from any but a given set of predeter-
mined directions. Since both light and
electron beams travel along straight
paths, the laws of geometric optics
apply irrespective of direction of travel
along this path. Consequently, parallax
barriers can be utilized where a viewing
screen is observed from predetermined
directions as in stereoscopic imagery,
or where a luminescent screen is im-
pinged upon by electron beams coming
from specified directions, as in color
television tubes. Parallax barriers are
now being used for both of these pur-
poses.

Presented on April 21, 1952, at the Society's
Convention at Chicago, 111., by Sam H.
Kaplan, Consultant, 3713 W. Arthington,
Chicago 24, 111.

Brief History

The concept of the parallax barrier
is generally attributed to Berthier1 of
France who suggested it in 1896. How-
ever it was first applied by Frederick E.
Ives1 to produce stereoscopic still pictures
in 1904. These were called "parallax
stereograms" and required no separate
viewing accessories. The substitution
of lenses as an alternate to mechanical
blocking barriers was proposed by
Gabriel Lippman of France in 1908.2
A barrier system with more than two
elements behind each barrier aperture
was invented by C. W. Kanolt who
obtained U.S. Patent 1,260,682 on
March 26, 1918. His stereoscopic pic-
tures were called "parallax panorama-
grams" and revealed a multitude of
stereoscopic views as the picture was
viewed from different angles. A radial
nonparallel-type barrier system was
invented by B. T. Ivanof3 who first

July 1952 Journal of the SMPTE Vol. 59

Fig. 1. Two-element barrier.

used it in 1941 to show projected stereo-
scopic motion pictures in Russia.

The use of parallax barriers as ex-
ternal attachments to cathode-ray tubes
for stereoscopic television is included in
several patents. The use of such
parallax barriers inside a cathode-ray
tube, as a positive means of insuring
that portions of a mosaic screen would
be subjected to bombardment only by
a predetermined electron beam, was first
revealed in German Patent 736,575,
issued June 22, 1943. The application
date is July 12, 1938, and the inventor
was Dr. Warner Fleshig of Fernseh A.G.

Principle and Geometric Relationships

The application of the parallax
barrier to stereoscopic pictures can serve
to illustrate the principle (see Fig. 1).
Two pictures taken from slightly sepa-
rated points of view and designated as
left and right views, are divided into
fine strips and reassembled on an
alternate basis: RI, L2, R3, L4, R5,
etc., (the odd numbered L strips and the
even numbered R strips are not used).
In front of the reassembled picture
(labeled "I" plane) there is placed a
series of opaque strip barriers separated

by transparent strips of equal width
(labeled "B" plane). If the barrier is
properly located between the picture
and the viewer's eyes (labeled Ot and
Or), the left eye will see only the strips
L2, L4, L6, etc., (the R strips being
hidden by the barriers). Likewise, the
right eye will see only strips R1} R3,
R5, etc. If the strips are of such small
width that they are not individually
resolved by the eye, a stereoscopic picture
results, since each eye sees only the pic-
ture corresponding to its field of view.

From simple geometrical considera-
tions it is possible to determine that the
relationship between image distance
(D), distance between image strip cen-
ters (I), separation of eyes (O), and
distance of eye plane to image plane
(C), is:

0 + 1

(1)

Although the distance between the eyes
(labeled as "O" points) and the image
increases steadily in going from the
center to the edges of the image, the
bandwidth of the picture strips and
barrier strips is constant and is inde-
pendent of the angle between any image

July 1952 Journal of the SMPTE Vol. 59

Fig. 2. Two-element barrier showing repeating "O" points.

Fig. 3. Alternate viewing of same element by different "O" points.

portion and the line of viewing. Proof
is given in an article by C. S. Szegho.4
The width (B') separating the barrier
strips can be determined from similar
triangles to be:

(2)

In this case the distance B between
barrier strip centers is 2B'.

The question arises whether there are
other points in addition to Oi and Or
from which the same picture (i.e., left
image seen by left eye and right image

seen by right eye) can be viewed. As
shown in Fig. 2, by projecting rays from
the image through the apertures be-
tween barriers, using in turn different
barrier spaces for a given image strip,
one can obtain an alternating sequence
of equally spaced Oi and Or points.
Any combination of d and Or points,
whether adjacent or nonadjacent, will
fulfill the condition that one "O" point
"sees" only one image set and the
second "O" point sees the alternate
image set. Figure 3 shows in more
detail the relationship between these

Sam H. Kaplan: Theory of Parallax Barriers

Fig. 4. Three-element barrier system;
second- and third-order barrier planes shown.

Fig. 5. One cycle of a six-element system.

Fig. 6. Reciprocal relation
between "O" and "I" planes;

1+6

July 1952 Journal of the SMPTE Vol. 59

different "O" points and a given image
strip. The only difference is that a
particular strip (in this case LI) is
"seen" by (Oi)i, by (Oi)2, and by
(Oi)3 through different barrier plane
apertures.

Barriers for More Than Two
Image Elements per Aperture

Instead of two viewing points (called
"O" points) coupled to two mutually
intermeshed image area sets, three or
more intermeshed image area sets can
be coupled to a corresponding number
of viewing points. Such an arrangement
is possible if the barrier has a ratio of
aperture area to total barrier plane
of 1/JV or less, where JV equals the
number of points coupled to a similar
number of sets of mutually exclusive area
elements. For a three-element arrange-
ment the width of the barrier member
must be at least twice that of the aper-
ture width; for a four-element arrange-
ment the barrier width is at least three
times the aperture width. A three-
element arrangement is shown in Fig. 4.
One section of a six-element arrange-
ment is shown in Fig. 5.

While the "O" plane has been con-
sidered up to this point as a viewing
plane, the various "O" points in the
"O" plane may also be considered as
origins of electrons or other radiation,
for the purpose of creating a parallax
system consisting of an image plane, a
barrier plane and an origin (or object)
plane.

In order to generalize the theory of
parallax barriers, consider the barrier
plane to be covered with a regular re-
peating dot pattern (such as the rec-
tangular dot pattern shown in Fig. 6).
If there is a point source of rays in the
O plane, the pattern in the barrier
plane will be projected on the image
plane I and will be enlarged in the

ratio of I _ Y If any particular

point in the above projected image
plane I is considered as an origin, then

it will project the barrier plane pattern
onto the O plane and the pattern will
be enlarged in the ratio of G/D. Any
dot in the resulting O plane pattern
can be shown to be in the correct
position for projection of the barrier
pattern onto the previously projected I
plane pattern. The different dots in
the O plane can be considered to corre-
spond to the (OOi, (Oi)2, (Oi)3 points
of Fig. 3. Thus we see that the patterns
of image and origin planes bear re-
ciprocal relationship to each other,
and the functions of O and I may be
interchanged. Mathematically:

1 = - +
B O T

(3)

where B, O and I are the pattern sizes
in the B, O and I planes, respectively.
The dots of these patterns serve as the
centers for the area patterns actually
used. Desirable area shapes and pat-
tern arrangements are discussed below.
To develop a two-element, a three-
element or an jV-element arrangement,
it is necessary to intermesh two, three
or JV patterns in both the image and
origin planes between each other.
Each image pattern is then coupled to a
corresponding mutually exclusive origin
pattern. Figure 7 illustrates a two- and
three-element arrangement.

Arrangements of Image Elements

Practical considerations call for the
maximum utilization of available area
in the image plane. Although many
geometrical patterns exist which can
cover an entire area, only a few meet
the two following criteria:

(1) The patterns must contain only
the same shape and size elements.

(2) All the elements must have the
same orientation.

Arrangements meeting these criteria
are parallelograms (including rectangles
and squares) and hexagons. Although
an area may be covered by isosceles
triangles, such an arrangement does
not fulfill the second criterion since

Sam H. Kaplan: Theory of Parallax Barriers

Fig. 7a. Two intermeshed patterns.

Fig. 7b. Three intermeshed pat-
terns; circle area elements also
shown.

Fig. 8a. Rectangular three-element
pattern.

Fig. 8b. Hexagonal three-element
pattern.

a l 3 '«/

•«

2 — -

X l|3

2.1 3

---£

2-1 3 X

"" x

Fig. 9a. Open barrier arrangements, Fig. 9b. Open barrier arrangements,

staggered. nonstazerered f bands).

I 2 3

2. 3 \

b. Triangular

Fig. 10. Preferred three-element origin
arrangements.

half the triangles have one orientation
and half are oriented 180° out of phase
with the first set. From a practical
point of view, ellipses (including circles)
may be considered to fulfill the necessary
conditions, although only 90.7% of the
available area is covered when these
are in the close-packed arrangement
shown in Fig. 7b.

nonstaggered (bands).

Classification of Barriers

Closed- and Open-Barrier Structures. It
is possible to classify parallax barriers
with respect to aperture boundaries.
The apertures can either meet or not,
and the barriers can then be called
"open" or "closed," respectively. In
the closed-structure type, each aperture
is completely surrounded by barrier.
Open-barrier structures consist of bands,
either straight or staggered.

Three-element arrangements can
utilize either open- or closed-type bar-
riers. In order to transform open
barriers to the closed-barrier type,
alternate image row areas must be
staggered 180° with reference to the
preceding row. Figure 8 illustrates the
image plane arrangement for rectangles
and hexagons to go with a closed-type
barrier. See Fig. 7b for a similar ar-
rangement for circles. Where rec-

July 1952 Journal of the SMPTE Vol. 59

tangles are used and the elements are
under one another, only an open-barrier
band-type arrangement is possible
(shown in Fig. 9).

In the three-element arrangement one
origin point is usually selected from
each of the three intermeshed O plane
patterns. For most purposes it is
desirable to choose the O points as close
together as possible. The three points
may be selected from three adjacent O
points in a single line, leading to a
"collinear" arrangement shown in Fig.
lOa, or the O points may be selected to
constitute the apices of a triangle — a
"delta" arrangement — leading to an
even closer pattern, as shown in Fig. lOb.

Higher Order Barriers. The barriers
already described have a reciprocal
arrangement between image, source and
barrier pattern centers. By looking
again at Fig. 4, one may see that there
are other possible barrier locations
(formed by ray intersections) which
fulfill the basic condition of having each
image area "seen" by only one of the
O points. These locations are shown on
the drawing as B2, B3, etc. and corre-
spond to the selection of nonadjacent
O points from a smaller submultiple O
plane pattern. The first barrier plane
shown has the O points taken from
adjacent points of a pattern having a
separation of distance O. The second
barrier plane corresponds to the selection
of alternate points of a pattern having
points separated by distance £O. The
third plane corresponds to the selection
of every third point of a pattern with
point separation of %O. This third
barrier plane cannot be used in a three-
element arrangement since it means
all three O points have been taken from
the same point set in the O plane,
instead of having one O point taken
from each of the three intermeshed sets.
Each O point would "see" the same
image set, and the other two image area
sets would be seen by none of the O
points. The formula for these other

image-to-barrier-plane spacings is given
as:

/TIC
0 + Kl

(4)

where K is the ratio of O distance to the
smallest O pattern spacing. When using
these higher order barriers, the elements
of a given image cluster are "seen" by
the O points through different apertures,
instead of through a single aperture as
is the case for the first barrier plane.

Nonplanar Barriers and Images. The
parallax barrier principle is not limited
to three parallel planes. Consider a
spherical surface I and two O points,
as shown in Fig. 11 a. The locus of the
intersections of pairs of rays which are
a fixed distance apart on the image
surface and pass through the two given

0 points will sweep out a curve which
meets the parallax criteria. This sur-
face will not be a sphere. In this case
the size of the elements on the image
surface is uniform. By sacrificing this
condition, any given barrier B and image

1 surfaces can be arbitrarily chosen to
meet the parallax condition for any
given O points. For example, in Fig.
lib, curve I can be a circle (in three
dimensions spherical) and curve B may
be a plane or a sphere with any given
radius. The patterns on I and B must
be constructed by a point-by-point
method. An example of a two-element
construction is illustrated in Fig. lla.
Starting with line 1 connecting O2 and
Ii, draw line 2 connecting d and B3
(the point of intersection of line 1 and
curve B), continuing on to curve I.
Line 3 then connects O2 and I2 (the
point of intersection of line 2 and I).
Line 4 connects Oi and B2 (the point of
intersection of line 3 with B), etc. In
other words, O2 lines connect with
previous intersection points on I and
Oi lines connect with previous inter-
section points on B. The examples are
shown in two dimensions. The three-

Sam H. Kaplan:

of Parallax Barriers

Fig. lla. Construction of spherical "I" and "B" surfaces, nonuniform elements.

"0"

°2

Fig. lib. Spherical "I" and plane "B» surfaces.

dimension arrangement necessary for
any practical use is more complicated.

The above analysis is based upon a
100% utilization of available image
area. It may be desirable to have both
fixed surfaces of given shapes and a
uniform pattern on one of the surfaces.
This can be done, but only by sacrificing
some of the image area. For example,
the surface I can be chosen as spherical,
and the barrier surface as a plane with
a uniform dot pattern. This can be
done if the aperture size in the plane
barrier is small enough to avoid over-
lapping patterns on surface I.

The Radial-Type Barrier. If the image,
barrier and source surfaces are planar,
they need not be parallel. The above
principles can be used to generate
nonparallel arrangements. One such
arrangement of interest is the radial

plane arrangement, invented by Ivanof
and used for stereoscopic pictures. As
shown in Fig. 12, all three planes meet
in a common line of intersection and all
band patterns of I, B and O planes
converge toward a single point on
this common line of intersection. For
motion pictures — the I plane comprises
the screen; the B plane, the parallax
barrier; and the audience, the O plane.
This arrangement permits a large
number of seats to satisfy the parallax
condition, in contrast to the parallel
plane arrangement where only one row
in the theater can meet the necessary
condition. Of course, if the rows could
be stacked vertically instead of hori-
zontally then the parallel plane arrange-
ment would be suitable.

The Venetian-Blind Barrier. Instead of
a separate barrier plane, the surface
itself can be shaped to provide the

July 1952 Journal of the SMPTE Vol. 59

Fig. 12. The radial barrier arrangement.

Fig. 13. Venetian-blind barrier.

necessary parallax condition as shown
in Fig. 13. The sides of the slats form
two of the three image areas. The
surface now resembles a Venetian blind.
The height of the slats is equal to the
distance D as in the other arrangements
and is determined by the construction
methods and formulae already given.

Physical Limitations

and How to Minimize Them

Light Loss Caused by the Barrier. One
defect in the practical application of

parallax barriers is the transmission
loss introduced by the barrier itself.
This limitation can be minimized by
replacing each aperture or slit by a
spherical or a cylindrical lens, as shown
in Fig. 14. Replacing the aperture by
a larger size lens can theoretically cut
the barrier loss to zero. Instead of acting
as a mechanical barrier, the lenses
refract or converge the rays to the proper
position on the image surface. In
stereoscopic picture processes modern
practice calls for cylindrical lens elements

Sam H. Kaplan: Theory of Parallax Barriers

°2

Fig. 14. Lens equivalent of barrier; finite "O" points shown.

Fig. 15. Effect of finite size of "O" to avoid overlapping;
"I" must be reduced to "I"', or "B"' must be reduced to "B'

molded into the film base. If one deals
with electron rays instead of light, elec-
tron lenses can be used, and the apertures
themselves can act as the electron lenses.
Owing to the focusing action, these
apertures, serving as electron lenses,
can be larger, thus increasing the num-
ber of electrons reaching the image
plane I. To make the apertures behave
as electron lenses, it is only necessary to
provide for an electric field between I
and B greater than between B and O.

Finite-Area Sources. All previous dis-
cussion has been on the basis of point
sources in the O plane. Actually,
especially in electronic apparatus, the
O points have appreciable area. In
order to ensure that each O point sees
only its own image plane patterns when
using barriers (rather than lenses), it
is necessary (see Fig. 15) to reduce
either the size of the barrier plane
apertures B' or the size of the image
plane elements I', in either case main-
taining the same separation distance
between apertures and image elements.
Figure 15 shows the proper geometrical

solution to achieve the nonoverlapping
condition of image areas. The reduced
sizes are by similar triangles:

(6)

where O' is size of O area and B' and
I' are the sizes of apertures and image
elements, respectively. The reduced
B* or I ' size will result in loss of efficiency
by reducing the number of rays from the
O points which can be utilized.

Practical Application of
Barriers in Cathode-Ray Tubes

The parallax barrier is particularly
suitable as an internal member in
cathode-ray tubes, permitting positive
screen area control and ensuring that a
given beam impinge only on a given
portion of the fluorescent screen. Speci-
fied screen areas are associated with a
desired source of electrons, and electrons
from other sources are blocked from the

July 1952 Journal of the SMPTE Vol.59

same area by the barrier. The control
is effected by the real or apparent
position of the electron source. Either
a separate electron gun is used for each
independent set of elements or the beam
originating in a single electron gun may
be successively shifted through the proper
O points. Such cathode-ray tubes can
be used in multitrace oscilloscopes
giving each trace a different color, or as
multicolor radarscope for differentiating
by color such things as moving targets,
radar beacons, etc. The most important
application, however, appears to be for
color television in two-, three- or four-
color sequential or simultaneous-type
systems. A large number of tricolor
picture tubes are being built on this
principle.4'5-6 At present the applica-
tion of the parallax barrier principle in
a cathode-ray tube represents the most
promising solution for an all-electronic
color television viewing device.

Acknowledgments

The author wishes to acknowledge
the advice and assistance of Dr. G. S.
Szegho and co-workers of the Rauland
Corp., Chicago, 111., in the preparation
of this paper.

References

1 . Josef Maria Eder, History of Photograph}!,
Columbia University Press, New York,
1945, p. 383.

2. Ibid, p. 669.

3. Denis Segaller, "The Russian stereo-
scopic cinema," Discovery, 355-358,
361, Nov. 1949.

4. C. S. Szegho, "Experimental tri-color
cathode-ray tube," Tele-Tech, 9: 34-35,
July 1950.

5. H. B. Law, "A three gun shadow mask
color kinescope," Proc. IRE, 39: 1186-
1194, Oct., 1951.

6. R. R. Law, "A one-gun shadow mask
color kinescope," Proc. IRE, 39; 1194-
1201, Oct. 1951.

Sam H. Kaplan: Theory of Parallax Barriers

New Direct- Vision
Stereo-Projection Screen

By W. WHEELER JENNINGS and PIERRE VANET

This paper discusses the development of a new direct-vision stereo-projection
screen. It permits the audience to see three-dimensional color motion pic-
tures and slides without the aid of conventional polarized viewing glasses.

J? OR MORE THAN half a century,
thousands of dollars have been invested
by researchers in the hope of developing
a good commercial free-vision stereo-
projection screen. The problems en-
countered have been very complex.

First, let us re-examine the mechanism
of our visual impressions. We see
objects in relief because of the perception
of each of our eyes of a point located in
space and observed at different angles
that correspond to the distance between
the eyes (Fig. 1). The convergent
action of our eyes enables us to estimate
by exploration the various distances of
different points located in space.

The image received on the retina of
the right eye is not the same as received
by the left eye. In order to get the
impression of relief, it is necessary to
project two views taken at different
angles and to avail oneself of means
that will enable each eye to see only the

Presented on April 22, 1952, at the Society's
Convention at Chicago, 111., by W.
Wheeler Jennings, 7549 South Clyde
Ave., Chicago 49, 111., and Pierre Vanet,
Societe des Anciens Etablissements, A.
Mattey, Paris, France.

picture it should receive at the exclusion
of the other.1

In order to get natural binocular
vision under our existing stereo-projec-
tion processes, it is necessary for the
spectator to wear special polarized or
red and green viewing spectacles.

We will deal here only with the
processes of stereo projection that give
us directly and collectively three-dimen-
sional screen images as seen with our
natural vision.

The Noaillon Theory

In 1928, Professor Noaillon, of Brus-
sels, Belgium, developed a selector sys-
tem, made up of radial converging lines
in the form of grills with very wide
openings. This system consists of three
reclining grills shaking or oscillating in
their own plane around their meeting
points, as shown in Fig. 2.

Figure 3 shows projection on screen
E through this radial-lined network
which determines the selective vision
surfaces. Starting from the stereo-pro-
jector G and D, representing the left
and right stereo images, the projected
image travels to the meeting point O

July 1952 Journal of the SMPTE Vol. 59

TsTzT,

Figure 1,

Figure 2.

\V\\\M» mi'' 'it.

FSSff

Figure 3.

Figure 4.

of all the lines T of the converging
grills. Direct-vision zones G2, D2, Gl
and Dl radiate on surface P. The
convergent setting of the selector grills
brought an important improvement in
the projected stereoscopic vision of
depth.2

The Findings of Russia's Ivanov

In 1945 and 1946, we had newspaper
reports of excellent 35mm stereo motion
pictures and free-vision theater projec-
tion in Moscow. Much of the informa-
tion sounded far-fetched, especially con-
cerning the technical means employed.

Since that date, a translation from
the Russian reveals most of the steps
used in their process: The screen em-
ployed was of lined network design
converging, similar to the Noaillon
theory shown in Fig. 2 and 3, but
Ivanov's network is stationary. This

weblike network shown in Fig. 4 con-
sists of more than 30,000 white enameled
wires stretched from the top of the
screen T to the meeting point on the
bottom O. The shaded portion is the
projected picture area. These wires
pull a total tension of 30 tons. The
total weight of the screen is approxi-
mately 6 tons. Figure 5 is a schematic
of Russian origin showing the vertical
screen format of the split frame. The
stereo-screen image is estimated to be
approximately 12 ft X 9 ft. Because
of the very narrow and limited vision
zones, the theater in which this screen
is installed seats only 250 people.

According to Ivanov, the theory of
Noaillon brought out the following
defects: (1) considerable absorption
of light and (2) a very narrow observa-
tion zone, which does not allow the
spectator to move his head. These are

Jennings and Vanet: Direct- Vision Stereo Screen

-9000

G 0
Figure 6.

all faults common to methods using
the fixed stretched network screen.

In an attempt to remedy these faults,
the Russians sought to achieve a se-
lector system consisting of conical con-
verging diopters. Unable to achieve
the diopters mechanically by means
used in optics, they tried to obtain the
results by photographic means, probably
by utilizing the properties of bichromate
on the film emulsion, which permits an
apparent relief.

Nevertheless, the Russians have made
a careful study of the momentous prob-
lems of stereoscopic motion pictures, but
they have struck a technical impossi-
bility in realizing a suitable selector of
transmission that does not produce the
faults of light absorption and diffraction
already discussed.

We have discussed the principal
obstacles stopping the use of lined
networks so that you will know of the
difficulties of direct-vision stereoscopic
projection.

Noaillon proposed to solve the prob-
lems by utilizing oscillating grills starting
with a selector system with much larger
openings between grills, which simplifies
the construction of the stereoscopic
network.

A New Direct- Vision
Stereo-Projection Screen

Francois Savoye, member of the
Commission of Color and Relief of the
French National Cinema Centre, solved
some of these problems in the design of
this new free-vision screen.

This system is based on the properties
of stereo-selection given by a rotating
conical shaped grill T as shown in
Figs. 6 and 8, moving around the
surface of the screen E. This is part
of the Noaillon theory with formation
of converging zones, on the plane
perpendicular to the plane on the screen.
This device enables the collective direct-
vision of stereoscopic pairs.3 The im-
pressions of relief are obtained in the
same manner as by natural vision.
Each spectator sees the right picture D
for the right eye and the left picture G
for the left eye. The rotating grill
driven by motor M produces total
shading, by persistence of vision sweeping
the screen, thus showing the whole
picture with all its detail in color or
black-and-white.

Figure 7 shows a 5-ft screen with a
projected stereo-image. This was photo-
graphed with a stereo-camera from the
spectator's seat.

For the sake of simplicity, we will
describe the engineer's model. The
revolving grill in Fig. 8 is constructed
of 108 aluminum bars forming the conical
section. The top support of the cone
is 36 in. in diameter. This accommo-
dates a beaded screen 18 in. X 24 in.
Each bar is set on geometric lines at

July 1952 Journal of the SMPTE VoL 59

Figure 7.

Figure 8.
Jennings and Vanet: Direct- Vision Stereo Screen

an angle of 20° to the screen. The
spacing must be accurate and the ratio
between the opening and the width of
the bar is 3 to 5 at the top and 2 to 5
at the bottom.

The path of the selector grill is so
designed as to have zones of vision
every four degrees as shown in the seat-
ing arrangement in Fig. 9. The correct
viewing distance is 2\ to 6 times the
width of the screen. It is simple to

Figure 9.

pre-set the seats in the vision zone of
40°. Rl, R2, R3, R4 and R5 repre-
sent the rows of seats. G and D repre-
sent the vision zones. OG and OD
represent the two images of the stereo-
projector. The spectator will naturally
keep himself in a suitable vision zone
that is not rigid, so he may move his
head slowly until the visual accommoda-
tions are most favorable.

The direction of rotation of the se-
lector grill is from left to right, turning
at a constant speed of four turns a sec-
ond. When projecting motion pictures
it was found necessary to use a syn-
chronous motor to turn the grill, to
eliminate any stroboscopic interference
with the projector's shutter.

The overall light-loss in projection on
the large screen shown in Fig. 7 is
estimated to be in the neighborhood of
50%.

This screen can be fabricated in most
sizes up to a 10-ft grill. We under-
stand, Mr. Savoye is now engineering

Figure 10.
July 1952 Journal of the SMPTE Vol. 59

a theater-size screen for an auditorium
seating 500.

The projector must be located behind
the spectator as illustrated in the upper
half of Fig. 10. When projecting a
very short distance, the screen should
be tilted forward about 5°. The lower
half of Fig. 10 illustrates the projection
of stereo-pairs from a single film by the
use of beam-splitter P mounted on the
front of the projector lens. The vision
zones Zl, Z2 and Z3 are the same as
shown in Fig. 9.

We will not attempt to discuss the
various types of beam-splitters and
lenses used in taking and projecting
16mm and 35mm motion picture stereo-
pairs. This is a specialized technical

subject that requires individual treat-
ment.

There is a great interest in color
stereo motion pictures. They have a
definite application in the fields of
education, industry and science. Every-
where three-dimensional color motion
pictures have been exhibited, they have
had a tremendous audience appeal.

References

1. Pierre Vanet "La prise de vue et la
projection en relief en vision collective
directe," Rev. photographie optique: p.
59, Mar. 1951.

2. Francois Savoye, "Vision direct," Rev.
photographie optique: p. 34, Dec. 1950.

3. Francois Savoye, "Les precedes de
cinema en relief," Rev. photographie.
optique: p. 23, Feb. 1951.

Jennings and Vanet: Direct- Vision Stereo Screen

Automatic Torque Controller
for Torque Motors

By CARL E. HITTLE

The use of the automatic torque controller permits the full advantages of
torque motors to be realized for film take-up and holdback duty without being
handicapped by their inherent limitations when operated in the conventional

THE FIRST sound-on-film re-
cording and reproducing units were
made, many types of film-spool drives
have been used on such apparatus.
During the intervening years, film-spool
drives ranging from the slipping belt to
friction clutch, and, more recently, to
torque-motor types have been used.
When torque motors became available
it was believed that they would provide
the ultimate in performance, possessing
more advantages than the previous types
of drives and none of the disadvantages.
Experience with these motors taught us
that in the latter respect this was not
true. As with the belt and the friction
clutch drives, we found that torque-
motor drives may also adversely affect
the steadiness of film motion in the
apparatus. Since the characteristics of

Presented on April 22, 1952, at the So-
ciety's Convention at Chicago, 111., by
Edward P. Ancona, Jr., for the author,
Carl E. Hittle, Radio Corporation of
America, RCA Victor Div., Engineering
Products Dept., 1560 N. Vine St., Holly-
wood 28, Calif.

torque-motor drives in connection with
their use for take-up and feed spools in
film-pulling mechanisms have been
presented previously before the Society
in a paper by A. L. Holcomb, * only the
manner in which they may affect film
motion will be reiterated. As stated
in Mr. Holcomb's paper, these adverse
effects may result from the following:

1. Sprocket-hole flutter (96 cycle/sec)
due to high film tension at beginning or
end of a reel.

2. Erratic shifting of the film with
respect to the sprockets at "crossover"
where the net tension on the film
reverses.

3. Gear train chatter due to unloading
the sprocket gears at crossover.

All of these contributing factors may
be eliminated by maintaining constant
film tension throughout the roll be-
tween each film spool and film sprocket
with a differential in tension between

* A. L. Holcomb, "Film-spool drive with
torque motor," Jour. SMPTE, 58: 28-35,
Jan. 1952.

July 1952 Journal of the SMPTE Vol. 59

the take-up side and the drag side,
tension on the latter side being of lesser
numerical value. Film tension may be
controlled and maintained within satis-
factory operating limits by means of the

automatic torque controller for torque
motors to be described herein. It is
equally useful whether .the motor is
used as a take-up or drag device. The
principle of operation of the controller

Fig.. 1. Torque Controller — front view.

Fig. 2. Torque Controller — rear view.
Carl £. Hittle: Automatic Torque Controller

is based on the fact that the torque
produced by the motor may be varied
by changing the voltage to the motor.

Principal elements of the controller
consist of the following: a film roll
follower mounted on a rotatable arm,
a multistep rotary switch actuated by
the rotatable arm, a set of resistors
having as many adjustable contact
bands as there are steps on the rotary
switch, a solenoid, a relay, and inter-
connecting wiring.

The film roll follower arm assembly is
mounted on the front side of the reel
panel as shown in Fig. 1. The re-
mainder of the mechanism is mounted
on the back side of the panel together
with the torque motor.

When used in conjunction with the
motor serving to drive the take-up spool
or reel, the device functions in the
following manner. Sufficient resistance
is introduced in series with the motor
at the start of the roll during take-up
to reduce the film tension to the desired
value. Thus the usual initial high
film tension is eliminated at the begin-
ning, thus removing this cause of
sprocket-hole flutter. The torque con-
troller functions in a manner to main-
tain film tension relatively constant. As
the diameter of the roll of film being
wound on the take-up spool increases,
the roller on the follower arm is moved
farther from the center of the spool,
causing the shaft to which the arm is
attached to be rotated. The rotary
switch contactor arm, mounted on the
opposite end of the shaft, is moved
gradually across the step contacts of
the switch shown in Fig. 2. Sufficient
free movement has been provided in the
mechanical assembly to prevent rota-
tional eccentricity of the roll of film
from causing oscillation of the contact
brush across adjacent switch steps.
The gradual operation of the rotary
switch causes small incremental de-
creases of resistance in the motor circuit
resulting in a gradual increase in motor
voltage. This, in turn, due to the

electrical characteristics of the torque
motor produces an increase in motor
torque.

As applied herein, torque may be
defined as the product of a force multi-
plied by a moment arm. In terms with
which we are concerned, film tension
and radius of the roll of film are the
force and moment arm members, re-
spectively, of the torque equation.

With proper adjustment of the posi-
tions of the resistor contact bands, the
torque may be controlled so as to main-
tain the film tension constant within
approximately 2 oz. Based on a normal
tension of 11 oz, the 2-oz variation is
less than 20% deviation. Should one
attempt to use 2000-ft rolls with standard
2-in. film cores on apparatus equipped
with friction clutch or standard torque-
motor take-up drives, the deviation
would be on the order of 600%. This
deviation in tension would be nearly
400% for 1000-ft rolls under the same
conditions.

The drag or holdback torque motor
functions in the inverse manner from
that for take-up. To prevent free-
wheeling of the roll of film with the
motor power off, a friction clutch is
incorporated in the mechanical as-
sembly of the motor and reel shaft.
Since this available friction is sufficient
to provide holdback as the diameter of
the roll of film approaches the core,
motor power is turned off when the roll
is reduced to a predetermined diameter.
This is accomplished by means of a
relay, shown in Fig. 3, which is energized
from the main motor switch that controls
the direction of film travel through the
apparatus. When the relay is energized,
the electrical connections between the
last two steps of the rotary switch and
their associated resistor contact bands
are opened. Then, when the rotary
switch arm contacts either of these
two steps, the electrical circuit to the
motor is opened. Also, when energized,
the relay causes additional resistance to
be imposed in the electrical circuit to

July 1952 Journal of the SMPTE Vol.59

R-l

Fig. 3. Schematic diagram of Torque Controller.

obtain the decreased torque required
when the motor is used for holdback.
Operation of the device in the above
manner serves to maintain a lower value
of film tension for holdback operation
than for take-up with no change re-
quired in the settings of the resistor
contact bands for change-over from
take-up to holdback duty.

Maintenance of holdback tension in
proper relation to the take-up tension
results in the elimination of: (1) re-
versal of the net film tension and its
resultant shifting of the film on the
sprocket plus gear train chatter, (2) high
film tension at the end of the reel which
otherwise would tend to produce sprocket-
hole flutter.

An automatic follower arm lift has
been provided to facilitate placement of

a reel or spool of film on the reel spindle
or removal therefrom. Lifting of the
arm to its extreme rotational position
from the spindle is accomplished by
means of the solenoid, shown in Fig. 3,
which is energized when the main motor
power switch is in its OFF position.

The automatic torque controller as
illustrated is suitable for use on mag-
netic recorder-reproducers or photo-
graphic reproducers having film handling
capacity on either reels or spools up to
2000 ft. Its use is particularly advan-
tageous in eliminating the extremely
high film tension which results when
2000-ft rolls wound on standard film
cores are used. Obviously the same
principle may be applied for reels of
larger diameter.

Carl £. Hittle: Automatic Torque Controller

Three-Phase Power
From Single-Phase Source

By A. L. HOLCOMB

Described is the development of a nonrotating device for the conversion of
single-phase 115-v power to a three-phase 230-v form for the synchronous
operation of cameras, sound recorders and other film pulling mechanisms
associated with production of motion pictures.

JL HREE-PHASE MOTORS provide several
desirable characteristics which are not
supplied by single-phase units of equiva-
lent power, and these characteristics,
which include smaller size, lighter
weight and quieter performance, are of
particular value for the operation of
cameras in motion picture production.
Unfortunately, three-phase power lines
are seldom available for location work
outside of the studio lot, whereas the
single-phase, 115-v source has become
readily available in a large percentage of
locations. Since sound recorders can
conveniently be driven by single -phase
motors, due to higher permissible noise,
and to less rigorous weight-space require-
ments than cameras, it has become ap-
parent that a synchronous converter
from single-phase, 1 1 5-v, to three-phase,
230-v, for camera operation would be
a desirable device. This would permit
the operation of all channel equipment

Presented on April 25, 1952, at the So-
ciety's Convention at Chicago, 111., by
John G. Frayne for the author, A. L.
Holcomb, Westrex Corp., 6601 Romaine
St., Hollywood 38, Calif.

from a single-phase source without
degrading camera performance.

A nonrotating device is preferable for
reasons of noise and maintenance and
while several such units are commer-
cially available for this duty, they are
not well fitted for camera drive since
they require factory adjustment for the
particular motor and load which the
unit is to supply. Operation with
other motors or different loads causes
phase unbalance which can create
operating noise and/or limit the maxi-
mum power obtainable from the motor,
thus destroying the very features for
which a three-phase motor is desirable.
Since most cameras used in motion
picture production vary widely in power
demand with temperature change, it.
is only by chance that the factory ad-
justed phase balance is optimum for
any given location condition. If the
maximum power condition of the motor
is selected for phase balance, an un-
balance and noisy operation exist for
all lesser loads while adjustment for
balance at light load reduces the maxi-
mum power obtainable.

July 1952 Journal of the SMPTE Vol. 59

TRANSFORMER T2

SINGLE PHASE

1 15V
INPUT

THREE PHASE
LOAD

TRANSFORMER Tl

Fig. 1. Simplified schematic of the Converter.

Thus, it appears that a satisfactory
single-phase to three-phase converter
for camera operation must provide
either a circuit that does not unbalance
when supplying different motors and
varying loads, or one which provides
some clear indication of unbalance and
a ready means of correction which is not
too complicated for field adjustment.

Consideration of the problem indicates
that the required phase shift from two
conductors electrically 180° apart to
three conductors displaced 120° cannot
be obtained on a nonrotating basis
without introducing reactance in various
forms in the conversion circuit. Since
the electrical load is also reactive, it
will combine with the circuit reactance
to determine the phase shift obtained
unless isolation can be introduced be-
tween the conversion circuit and motor.
Adequate isolation does not appear to
be practical because of space-weight
and efficiency factors and thus the
motor reactance which varies from
motor to motor and with load on any
given motor must be considered as a
component part of the conversion cir-
cuit. Therefore, a conversion circuit
which will inherently maintain phase
balance in the presence of the prescribed
conditions is not considered practical,
and as a result development has been
focused on the alternative method,
which would provide convenient indica-
tion and adjustment.

Basic Circuit

The Scott transformer connection,
which is relatively old in the art and
described in most electrical engineering
handbooks, is the basis of the conversion
circuit shown in Fig. 1. This trans-
former connection was originally used
for the conversion of two-phase to
three-phase or vice versa. By the
addition of a capacitor of the right value
in series with the primary of trans-
former T2, as shown in Fig. 1, the cur-
rent in this primary can be shifted 90°
with respect to the primary of Tl and
thus the equivalent of a two-phase
primary circuit is provided from a
single-phase source. In the secondary,
a three-phase electrical displacement
exists only when connected to a balanced
three-phase inductive load, which is the
load condition presented by a three-
phase motor.

The circuit functions to produce
120° phase displacement between the
three output leads by means of the vector
addition of both a proper voltage and a
90° phase shift with respect to the
mid-tap of Tl. A portion of the in-
ductive load is reflected through T2
where it is effectively resonated at line
frequency by the series capacitor. This
provides the 90° phase shift mentioned,
since at resonance there will be no
reactive component in the primary of
T2 and the current will be in phase

A. L. Holcomb: Three-Phase From Single-Phase

Fig. 2. Schematic of the Converter.

with the voltage. The current in the
primary of Tl will lag approximately
90° since it is predominantly inductive.
The secondary voltages of Tl and T2
will thus be 90° out of phase and if the
secondary voltage of Tl is made 230
v and that of T2 is 200 v, then the
voltage between the lead marked Phase
1 and either Phase 2 or 3 will be:
£ri/2 + J'ETZ or 230 v. As combined in
the load, the currents in all three phases
are approximately 120° apart.

From the above it becomes apparent
why such circuits require adjustment to
a specific load condition since a variation
in either phase or voltage of the second-
ary of T2 will upset the three-phase
balance and both factors will vary with
any change in impedance or inductance
of the load. It also becomes apparent
that this correction must provide a
separate adjustment of the capacitor to
match the load inductance in addition
to a voltage correction for T2.

Developed Circuit

Development of the basic circuit for
actual use is shown in Fig. 2. The

transformers Tl and T2 appear in the
same form as in Fig. 1, but the single
capacitor is replaced by six units (C2
to 7) of such sizes that they provide
any value from 1 to 60 juf in \-yS. steps
and are readily connected as required
by means of individual switches. These
are oil filled a-c capacitors rated at
330 v. An additional capacitor shown
as Cl is an a-c electrolytic unit of
100-/zf capacity normally connected in
parallel with the others through the
relay SI. This is a necessary feature
since the impedance of a synchronous
motor is very much lower at the instant
of starting than when running; there-
fore, the capacitance required to ap-
proach resonance at line frequency is
several times greater at start than is
desirable for running phase balance at
even maximum load. Unless this initial
high capacitance is provided, the output
is essentially single-phase and the motor
will not start. Gl meets this condition
for the short start time and is auto-
matically disconnected by the relay SI
when the voltage across the primary of
T2 reaches 100 v. The current supply

July 1952 Journal of the SMPTE Vol.59

to the coil of SI is rectified to avoid
chatter of the relay contacts at break.
The coil of relay S2 is in parallel with
that of SI through a resistance which
prevents operation of S2 unless or until
the voltage rises to 300 v. This pro-
vides protection for the running con-
densers in case the load is disconnected
while the operating switch Dl is closed.
Opening the output circuit of phase 1
allows the voltage of the resonant circuit
in the primary of T2 to rise well above
the condenser rating unless this pro-
tection is provided. S2 in turn operates
the relay S3 which opens the input
circuit and locks up in this position
until the input potential is removed.

Tap changing on T2 was considered
as an alternative method of resonating
the primary with a single condenser,
but this was abandoned since tap
changing in such a resonant circuit
causes excessive arcing, and because
adjustment equal to that obtained by
six condensers and switches would
require a sixty-point tap switch.

Voltage adjustment for T2 may be
obtained without phase shift by means
of series resistance in the resonant
circuit or by resistance shunted across
the primary of T2, but either method
results in serious PR losses. The Variac
T3 when connected across the input
line, as shown, functions as an efficient
voltage divider and does not contribute
a reactive component to the resonant
circuit since the exciting current is
supplied by the line. Also, the range of
adjustment is wide and very smooth.

The three small voltmeters Ml,
2 and 3 are the indicators used to
determine and maintain phase balance.
M2 is a 150-v meter connected across
the incoming line which serves as a
pilot meter on the single-phase supply,
and also effectively indicates the voltage
across phase leads 2 and 3 during
operation since this voltage is twice the
line voltage except where a heavy load
may introduce appreciable PR loss in
Tl. Ml and M3 are 300-v meters

across the other two output phases.
With this arrangement, both three-
phase output and single-phase input
are shown in addition to the basic
function of balance indication.

Adjustment and Operation

The selection of the proper capacitance
in the primary circuit of T2 need only
be determined once for any given motor
and line frequency. Therefore, this
information may be obtained in the
shop before the camera goes on the set
or location. Once obtained, the con-
denser values for different motors, or
combinations of motors, may be tabu-
lated and attached to the converter
for ready reference.

To determine capacitor value, the
motor is connected for operation, pref-
erably driving a camera or other normal
load. The condenser values of 1, 2,
4, 8, 15 and 30 /-if are marked on the
plate adjacent to the switches which
connect them in parallel. Thus, the
values shown are additive as the switch
handles are toward the marked plate.
About 25 /uf should be connected as a
preliminary value of capacitance for
60-cycle operation (approximately 35
juf for 50-cycle). The Variac is posi-
tioned about center and the motor
started by closing the "line" switch Dl.
The two outside meters Ml and 3 are
then observed and the Variac adjusted
until they read alike. If this balanced
reading is higher than the pointer
position of the middle meter M2 (twice
the indicated voltage) then the capaci-
tance should be reduced, or vice versa,
and Ml and 2 again balanced by
Variac adjustment. This is continued
until all three meters show the same
pointer position. With very little prac-
tice this adjustment can be accomplished
in less than a minute. Having estab-
lished and noted the capacitor value
the unit is ready for operation; further
adjustment for load variation being
made by changing the Variac to make
the pointer of Ml read the same as

A. L. Holcomb: Three-Phase From Single-Phase

TRANSFORMER
PRIMARIES

SOLID LINES = NO MOTOR LOAD
DOTTED LINES = IOOW MOT.OR LOAD

30 OUTPUT
Fig. 3. Phase-voltage relations — without load correction.

1 15V

TRANSFORMER
PRIMARIES

SOLID LINES = NO MOTOR LOAD
DOTTED LINES = I60W MOTOR LOAD

30 OUTPUT

Fig. 4. Phase-voltage relations — with load correction.
July 1952 Journal of the SMPTE Vol.59

M2 ± a few volts. In either initial
or subsequent balancing, it will be found
that both Ml and M3 vary in the same
direction with each other and with the
Variac. However, Ml, across phase 1
and 2, varies more rapidly than M3,
and M2 does not change except with
input voltage.

In operation, the converter may be
located at the camera and the "line"
switch Dl used as the camera operating
switch, or the unit may be positioned
at the recorder with any individual or
common switching desired. In mild
weather where temperature and camera
load do not vary greatly, the initial
load adjustment of the Variac might
well remain the same for several days
shooting. In case of cold weather,
however, some cameras will warm up
enough in a long take to change load
by a factor of 2 or 3. Adjustment of the
Variac to meet this condition may be
made during a take without disturbance
to either picture or sound. It should
be noted, however, that precise adjust-
ment is not essential to operation and
under average conditions the unit can
be forgotten unless the camera motor
becomes noisy or lacks power.

Where recorder and camera are
both operated from the converter, either
motor may be dropped off at will. The
phase balance will be materially upset
and the remaining motor will be noisy
but the recorder is usually too far from
the microphone to cause trouble, and
if the recorder is cut off, the camera noise
does not matter.

Performance

It is obvious that the voltmeters used
as indicators of phase balance actually
show only voltage across the three phases
and indicate phase relation indirectly
if at all. Thus, this method of indica-
tion may well be questioned. Since
the voltages indicated are each a re-
sultant of two voltages to the mid-point
of the load, which in turn are the
resultant of a vectorial addition of both

voltage and phase relation, the theo-
retical reasons why such indications are
of value become involved and tedious
and will be omitted in favor of measured
results.

A true picture of the voltage condi-
tions in the load can be obtained by
measuring the voltage from each phase
lead to a mid-tap on a star connected
load. In addition, a method was
devised which indicated voltage phase
relations across the same points, and
across Tl and T2 primaries, to an
accuracy of db£°. The currents in
each leg of the load are not in phase
with the voltage but bear the same
relation to each other as the voltages
since the load is electrically symmetrical.
With the above arrangement, it was
possible to obtain an accurate picture
of phase-voltage relations under varying
load conditions.

A motor fairly typical of three-phase
synchronous camera motors was oper-
ated through the converter from a
115-v single-phase source and adjusted
for capacitance balance at no-load in
the manner previously outlined. The
accuracy of balance in each case was
probably of the order of ±2 v; about
what would be expected in normal use.

Figure 3 shows the phase-voltage
relations without correction for load
change. In Fig. 3A the primary of T2
is compared to the primary of Tl which
latter is also the line input and does
not change with load. The solid line
shows T2 at 140 v displaced 89° from
Tl when the motor ran no-load. When
the load was increased to just under
pull-out, the voltage dropped to 112 v
across T2 and the phase relation to
Tl became 75° as shown by the dotted
line. In Fig. 3B of the same figure is
shown the resultant conditions existing
in each phase winding of the motor. At
no-load as again shown by the solid
lines, the voltages to the mid-point
were between 131 and 134 v with
phases 121, 121 and 118° apart. With
100-w load on the motor, phase 1 has

A. L. Holcomb: Three-Phase From Single-Phase

Fig. 5. Engineering model of the Converter.

dropped to 104 v and shifted to 107°
from phase 1 and 131° from phase 3,
phase 2 has dropped to 118 v while
phase 3 has shifted 4° and increased
voltage slightly. As a result, the motor
was noisy and the maximum stable
power obtainable was reduced from
160 w mechanical to 100 w or 62 \%
of normal. This was chiefly due to the
changes in phase 1 with some con-
tribution from the reduced voltage in
phase 2; the voltage change and phase
shift of phase 3 being of little importance.
In this connection it was found that

unbalance of 10 v between phases, or
5 to 6° departure from the ideal, did
not create noticeable noise or power
reduction unless these factors combined.
Figure 4 is similar to Fig. 3 except that
correction for increased load was made,
as described, by means of the Variac T3.
In Fig. 4A the phase shift and voltage
change in the primary of T2 is small,
being 2° and 4 volts, respectively. In
Fig. 4B the phase shift in the motor
windings is negligible (3° maximum)
although some voltage unbalance exists
due to an increase in voltage of phase

July 1952 Journal of the SMPTE Vol.59

2 while phases 1 and 3 are reduced
alike. This unbalance is not too serious
and it appears only when capacitance
balance has been made at no-load and
load correction has been stretched to
cover the whole power range of the
motor. It should be noted in this
connection that the motor load is
160 w under the conditions of Fig. 4
which is the same maximum power
which this motor can deliver from a
normal three-phase line.

Power Characteristics

Power output capacity sufficient to
handle any motor or combination of
motors would be desirable. Since this
cannot be provided in a portable device,
the maximum weight which can be
carried by one hand (about 50 Ib) was
used as a base, and as much power as
possible was provided within this limi-
tation rather than selection of some
arbitrary value of power. The result
of this approach is a power output of
about 400 va; the real watts and
available mechanical power being deter-
mined by the power factor and efficiency
of the motor. The engineering model
is shown in Fig. 5.

The single-phase input power factor
is relatively good and varies from 50
to 95%, while the conversion efficiency
from single-phase to three-phase varies
from 30 to 75%; both factors depending
on the characteristics of the motor load.

In terms of equipment which can be
operated by the converter, the following
motors or combinations of motors appear
to be within the power handling range
of the unit:

Standard camera, synchronous motor —

limited only by motor power
Standard camera and portable recorder,

synchronous motors — above 50 F

ambient
Standard camera and portable recorder,

multiduty motors — any weather

Technicolor camera — above 50 F
ambient

As previously noted the load demand
of most cameras varies widely with
ambient temperature and the weather
is thus noted as a limiting load factor
in some cases. Multiduty motors * oper-
ated in the synchronous mode function
at relatively high efficiency and good
power factor and thus heavier loads
and/or more motors are operable from
the converter than is the case with the
usual variable reluctance synchronous
type. It should be noted that the
inclusion of this converter in a multi-
duty equipped channel adds single-
phase, 115-v supply to the existing
battery and three-phase power sources
frpm which such channels can operate.

Conclusion

The development of a portable, non-
rotary converter to supply three-phase,
230-v from a single-phase, 115-v source
has seemed desirable in order to realize
the inherent advantages of three-phase
motors, particularly on motion picture
cameras, while utilizing the convenience
and availability of single-phase source
of supply. Good phase-voltage balance
is essential in such a device under vari-
able load conditions, and it has been
possible to obtain this by providing a
simple form of indication together
with a ready means of correction.

Discussion

William P. Kruse: Approximately what
is the primary voltage on your resonant
transformer during some various normal
loads?

(Communicated by} A, L. Holcomb: The pri-
mary voltage of T2 is maintained essentially
constant at 135 volts by adjustment of the
Variac, as described, to meet the various
load conditions.

* A. L. Holcomb, "Motor systems for
motion picture production," Jour. SMPE,
42: 9-33, Jan. 1944.

A. L. Holcomb: Three-Phase From Single-Phase

Continuous Arc Projector
Light Meter

By HARRY P. BRUEGGEMANN

This is a system for monitoring the light output of an arc projector during
projection. It comprises a piece of optically flat glass, not silvered, placed in
the projector light path, at an angle of 45°, and ahead of the film gate. The
light thus thrown off to the side is measured by a photovoltaic light meter.

.RC PROJECTORS are normally built
for theater projection, and they are
designed to give a picture of pleasing
quality. However, when arc projectors
are used as laboratory production
equipment for timing prints or for side-
by-side comparison of prints, they must
meet certain rigid specifications. One
of these is the maintenance of an abso-
lutely steady light output.

Experience at Cinecolor has been
that arc projectors vary in their light
output by as much as 20% during a
10-min projection, in spite of good
operational practices and frequent equip-
ment maintenance. This variation, of
which the projectionist has no indication,
seems to be due to the carbon feed,
slight imperfections in the carbons
themselves, voltage fluctuations and
mechanical variables. A 20% change
in light output would probably never

Presented on April 22, 1952, at the So-
ciety's Convention at Chicago, 111., by
George W. Colburn for the author,
Harry P. Brueggemann, Cinecolor Corp.,
2800 W. Olive Ave., Burbank, Calif.

be noticed in a theater, provided it is
gradual enough. To a timer though,
who is attempting to adjust scene
densities to within one-half of a printer
point of what the producer wants, a
change of this magnitude is too great.

A number of systems for controlling
the arcs were investigated. One such
system consisted of a photoelectric cell,
the output of which would control a
thyratron, which in turn would control
the carbon-feed motor in such a manner
as to maintain a constant luminosity.
This has the advantage of being auto-
matic, the control being maintained
without requiring an adjustment by the
projectionist. As far as could be de-
termined, there was no such thyratron
arc controller on the market, hence it
would have to be designed. Since
Cinecolor already had some experience
in designing thyratron controlled light
sources, it was realized that this under-
taking would be very expensive. All
types of photoelectric light meters were
eliminated, also, because of design
expense.

July 1952 Journal of the SMPTE Vol.59

The only system which seemed feasible
would make use of a photovoltaic cell
type of meter so arranged as to keep
the projectionist continually informed
as to the light output of the projectors.
With this guide, he could maintain the
light at the standard value by trimming
the arc. A photovoltaic cell is practical
because it maintains its calibration
quite well if protected from heat,
moisture and intense light. Since a
great deal is known about the use of
photovoltaic cells as light meters, design
of such a system should be relatively
simple.

Accordingly, a projector light meter
was built around a photovoltaic cell.
In order to monitor the light actually
reaching the screen, a piece of unsilvered,
optically flat glass was placed in the
light path at an angle of 45°. This
threw a beam of light off to the side of
the projector, amounting to approxi-
mately 10% of the total output. This
was more than enough for any photo-
voltaic cell, and at the same time caused
a loss of only 10% in the screen bright-
ness. This could be compensated for
by trimming the arc. Obviously, the
glass had to be positioned between the
arc and the film gate.

The photocell was a Weston Photronic
cell type RR, and the associated am-
meter was a 0 to 20-/*a, 2500-ohm
Weston meter. Since the light from
the optical flat was far too much for
the cell, a means of attenuating this
light was necessary. A dense green
glass was placed ahead of the cell in the
first model. This cut down the light
to a workable level, but permitted a
great deal of infrared radiation to be
transmitted. This infrared energy
raised the temperature of the cell too
high for stability, so an Aklo heat glass
was added. This promptly cracked.
Thus it was evident that another means
of reducing the heat was necessary.
Ventilation slots were cut into the
casting holding the cell, and this helped

some, but the Aklo glass still would not
stand up.

At this point the projectionists at the
M-G-M laboratory, who had been in-
formed of our project and had built a
model of their own, thought of replacing
the dense glass filter by a sheet of brass
shim stock with pinholes. This solved
the excess heat problem, since the
infrared radiation was reduced as much
as the light. The first Cinecolor model
used a bakelite mounted photocell, but
M-G-M used a metal-encased cell for
conduction cooling. The M-G-M modi-
fications resulted in a cell mounting
which was only slightly warm to the
touch, even after many hours of con-
tinuous operation.

The Weston microammeter, with its
2500-ohm resistance, gave a fairly
linear response when coupled to the
type RR Photronic cell. Various de-
vices were considered for improving
the linearity, including shunt resistances,
lower resistance ammeters, and other
types of photocells; but they all re-
quired more light, and consequently
would have placed more heat at the
photocell. Since heat dissipation was
the biggest problem of the project, it
was decided to accept the slight non-
linearity. The only advantage to im-
proving the linearity would be to
eliminate the scale compression in the
operating range and thus increase the
sensitivity. With the present model of
the meter, however, luminosity fluctua-
tions can be kept within about 3% and
this is considered good. Most of this
fluctuation is due to the coarseness of
the trim, not the accuracy of the meter.

The location of the unit in the pro-
jector is shown in Fig. 1. This view
shows the first Cinecolor model mounted
in a Simplex projector, just above the
framing knob. The rear end of the
photocell, showing the bakelite casing,
is seen together with the two wires
leading to the microammeter. The
ammeter is mounted on the wall of the
projection booth just below the viewing

Harry P. Brueggemann: Continuous Arc Projector Meter

Fig. 1. View of the first Cinecolor model mounted in a Simplex projector.

THREAD- UP LAMP
HOUSING

-PHOTOCELL

ATTENUATOR

GROUND GLASS

MtCROAMMETER

Fig. 2. The three basic units of the second Cinecolor model.
July 1952 Journal of the SMPTE Vol. 59

r-REFt-Ecr.-

Fig. 3. Schematic of system — top view.

port, so that the projectionist can see
the screen and the meter at the same
time. Figure 2 shows the three basic
units of the second model — the optical
flat and brass attenuator mounting,
the metal-encased photocell, and the
microammeter. The optical flat occupies
the space normally used by the thread-up
lamp when it is lowered for threading
up. The lamp was repositioned so that
it missed the optical flat when lowered.
The perforated brass attenuator slides
into a slot cut just ahead of the photocell
housing. The edge of the attenuator is
visible in the figure. There is a ground
glass immediately behind the attenuator
to break up the light through the pin
holes, and thereby avoid any local
"hot spots" on the surface of the photo-
cell. Figure 3 is a schematic drawing of
an arc projector with the unit installed.
In operation, the system requires only

a 5-min warm-up period in the morning,
after which it will remain constant all
day. The warm-up is necessary because
the photocell has greater sensitivity
when cold, and temperature equilibrium
must be reached before the system
stabilizes. During projection, the opera-
tor needs only to keep the needle at a
constant standard value by appropriately
trimming the arc. The use of this
system has resulted in a great improve-
ment in projection quality, both at
Cinecolor and M-G-M.

Thanks are expressed by the author
to James Phillips, Chief Projectionist at
Cinecolor, for initiating and doing most
of the original work in this project,
and at M-G-M to Merle Chamberlain,
Chief Projectionist, and Clayton C.
Troxel, Jr., Projection Engineer, for
their modification which contributed to
the success of the final model.

Harry P. Brueggemann: Continuous Arc Projector Meter

Use of a Rotating-Drum Camera for
Recording Impact Loading Deformations

By D. F. MUSTER and E. G. VOLTERRA

The details of a rotating-drum camera are described. The camera is used to
record displacement-time data for short cylindrical specimens made of a
rubberlike material which are subjected to compressive impact loadings
lasting from 5 to 20 milliseconds. The auxiliaries to the camera are discussed
in light of the particular needs of a study being conducted on the dynamic
properties of plastics and rubberlike materials.

LN INVESTIGATION on the dynamic
stress-strain properties of plastics and
rubberlike materials is bein£ conducted
at Illinois Institute of Technology under
the sponsorship of the Mechanics Branch,
Office of Naval Research, as part of
their basic research program on the
properties of materials.

For determining directly the stress-
strain curves of plastics and rubberlike
materials subjected to impact loads,
the duration of which are of the order
of milliseconds, a special apparatus has
been built which uses mechanical and
optical devices. The paper is confined
to only a brief description of the optical
parts of the apparatus, and particularly
of a special rotating-drum camera and
its accessories which is used to record
displacement-time data for the speci-
mens being tested.

The apparatus employed in the experi-
ments is shown in Figs. 1, 2 and 3. It
consists essentially of:

Presented on April 23, 1952, at the So-
ciety's Convention at Chicago, 111., by
D. F. Muster and E. G. Volterra, Dept.
of Mechanics, Illinois Institute of Tech-
nology, Chicago 16, 111.

(1) two 3-ft, 1-in. diameter steel
bars, of equal mass, suspended as
ballistic pendulums;

(2) a rotating-drum camera, the drum
of which rotates at a known speed, and
the shutter of which is synchronized to
operate with the motion of the steel
bars;

(3) an optical system which focuses
the image of a very thin slit on the knife
edges machined on the adjoining ends
of the steel bars; and

(4) an electromagnetic device which
can release one or both of the bars at
the same time.

The cylindrical specimens of plastics
or rubberlike materials to be tested are
\ in. in diameter and \ in. long. They
are placed on the plane end of one of the
steel bars such that the longitudinal
axes of the bar and of the specimen
coincide. The other steel bar is released
from a predetermined height by a
magnetic release mechanism and is
made to impinge upon the free end of
the specimen. During the impact a
photograph is taken of the interval
between the knife edges which lie in
the plane of the ends of the steel bars.

July 1952 Journal of the SMPTE Vol.59

Fig. 1. Front view of camera.

A,. Push Button Control
E.« Projection lAap Switch
C.,Blow«r Motor Switch
D . .Tflyratron Extinguish

Control
E«. Delay Clrcait, Fii»

F,. Camera Motor Switch
G,. Belay Circuit Switch

Fig. 2. Back view of camera.
Muster and Volterra: Use of a Rotating-Drum Camera

MICROSWITCH

• — O-

BAR-

V
PIVOT

(on camera)

Fig. 3. Schematic diagram of equipment arrangement.

The magnetic release mechanism is
controlled electrically by a cam device
(shown on the camera shaft in Fig. 1),
which serves to time the release of the
bar with the position of the film on the
drum. This insures that the exposed
strip of film will not include the overlap
region where the two ends of the film
are joined.

A delay circuit is adjusted so as to
cause the shutter mechanism to operate
during the time interval of from 5 to
20 msec during which the impact
between bar and specimen occurs. The
record on the film strip is calibrated by
superposing a still photograph of the
distance between the two knife edges
when both bars are just in contact
with the specimen.

The data on the film strip are read
by direct measurements made with a
microscope mounted on a movable base.
The base is fitted with two orthogonal
motions and can transverse a maximum
of 4.5 in. in increments of 0.001 in.
From these data the displacement-time
relationship is plotted.

The camera body is made of J-in.
thick aluminum alloy plates. Front
and back views of it are shown in Figs.
1 and 2. All joints have been sealed

and the entire assembly painted dull
black. The back of the camera body
is mounted on hinges which permit easy
access to the drum. The back is
locked in position by four trunk-type
fasteners and is light sealed by a i^-in.
thick neoprene gasket cemented to its
inside surface.

The drum was turned from a 2-in.
cold-rolled steel plate and its finished
dimensions are indicated in Fig. 4.
It is mounted in the camera on a keyed
shaft with a large hex nut to facilitate
easy removal in the dark. The film
is placed on the inner surface of the
drum and held in position by two spring-
metal strips which grip the film strip at
its edges. The drum accommodates a
48-in. length of film, which permits a
slight overlap, and there is a useful
length of approximately 40 in. of film.

In the drum periphery there are two
f-in. radial holes that are used to focus
the slit image on the film strip. There
is a corresponding hole fitted with a
sealing flap in one end of the camera
body.

The drum- is driven by a small induc-
tion motor rated at ^ hp at 900 rpm.
Through a belt and pulley arrangement,
the speed of the camera drum is reduced

July 1952 Journal of the SMPTE Vol. 59

15.13" DIAM FROM FILM TO FILM.

j" DIAM
HOLE

—0.13"

Fig. 4. Rotating drum.

TOP VIEW

Fig. 5. Schematic diagram of optical system.

P.... Projection Lamp, GE 750T12P

G . . . Ground-Glass Plate, 2 in. X 3 in.

S... .Slit, 0.001 in. X | in.

K. . .Knife Edges on bars

M. . .Mirror, first-surface set at 45° to axis
of lens arrangement

F . . . . Film, Kodak Linagraph Panchro-
matic LP421

LI. . .Condensing Lens, 6in. //1, 4 ^in.diam
L2 ... Projection Lens, 75mm //I, 49mm

diam coated achromat
L3. . .Piano Convex Field Lens, 17 in. //I,

3^ in. diam
L4. . .Piano Convex Field Lens, 21 in. //I,

3^ in. diam
L6. . .Camera Lens, Color Skopar// 3.5, 105

mm //I

Muster and Volterra: Use of a Rotating-Drum Camera

to about 120 rpm, an adequate speed
for the shortest time during which
impact occurs. The actual speed of
the drum is measured just before and
after each test by means of a Jagabi Speed
Indicator accurate to within i of 1%.

The optical system from light source
to film on the camera drum is shown in
Fig. 5. There is every possibility that
other equivalent systems could be
designed; however, the one shown in
the figure was developed from the equip-
ment and materials most readily at hand
after a trial-and-error period in which
the design was changed several times.

The light source (not shown in Fig. 1)
is mounted in the air stream of a centrif-
ugal air blower immediately behind the
cylindrical tube which contains the
condensing lens, ground-glass plate,
slit, and projection lens, in that order.
The impact phenomenon occurs be-
tween a pair of field lenses, the first of
which serves to collimate the light rays
and the second, to focus the collimated
rays on the surface of the objective
lens. The light path between the field
lenses is partially blocked by the knife
edges on the bar ends, the distance
between the edges at each instant of
time indicating the deformation in the
specimen.

The camera lens, a Color Skopar I,
//3.5, 105-mm coated lens, focuses
the slit image on the film by means of
a first-surface mirror set at 45° to the
axis of lens arrangement. The image
is brought into focus by viewing it on
a piece of exposed film set over the
holes in the drum and the camera case
(see Figs. 1 and 2).

There are two electronic circuits
which are important to the proper
operation of the camera:

(1) the timing circuit of the bar
release mechanism; and

(2) the shutter delay circuit.

The former operates through a cam on
the shaft of the camera and times the
release of the impinging bar so that the
exposed strip of film will not include the

region of the splice. In order that the
bar will be released two contacts must
be closed, a pushbutton controlled by
the laboratory technician and the cam
timing contact which is preset. It is
expected that the bars will have essen-
tially the same periods from release to
initial impact for all anticipated values
of drop height. Thus, the cam setting
should not have to be changed, except
for minor adjustments, until very large
drops are attempted.

The shutter delay circuit, as its name
implies, causes the shutter mechanism
to open the shutter just prior to the
instant of initial impact. The actual
exposure time is governed only by the
speed of the drum and is preset on this
basis.

Thus far, Kodak Linagraph Pan-
chromatic LP421 film and Dektol
(D-76) developer have been used with
good results.

Summary

The rotating-drum camera described
here has been built to record an impact
phenomena, which occurs in from 5 to
20 msec, in order to determine directly
some of the dynamic properties of
rubberlike materials at high rates of
compressive straining. The optical ad-
vantages of a one-to-one slit-image relay
system are utilized to produce, on a
film strip, direct displacement-time data
which could not be obtained by any other
means.

Electronic circuits are provided to
time the release of the ballistic pendulums
with the proper position of the film
in the camera and to delay the opening
of the shutter until just before the
instant of initial impact.

Acknowledgment

The authors wish to thank R. E.
Lewis, Physicist, Armour Research
Foundation, and R. A. Einweck and
C. R. Olson, Illinois Institute of Tech-
nology, for their help on this and other
phases of the project.

July 1952 Journal of the SMPTE Vol. 59

The Navy's Training Film Production Program

And a Description of U. S. Naval Photographic Center
Film Depository Facilities Available to Commercial Film
and Television Agencies

By WILSON R. GRONENWETT and WILLIAM M. TIMMONS

The production of a motion picture is traced from the request stage through
the Navy Film Board of Review, to production by either commercial con-
tractor or the Navy Photographic Center. Film distribution is described,
and also the special photographic services available to the film and television
industries by the Naval Photographic Center's film depository.

T.
HE NAVY'S film production program

grows out of a need. The Navy has
many training schools, special activities
and, of course, the fleet. In all these
places men must be trained efficiently
and effectively in the skills and knowl-
edges of Navy work. These are in-
tensely practical needs.

In the past, the apprentice system
has been an excellent method of meeting
such needs. An inexperienced man
worked alongside a trained man and
gradually gained the same skills and
knowledge through observation, active
learning and correction of mistakes
pointed out by the trained man. The
apprentice system, however, was slow,

Presented on April 22, 1952, at the So-
ciety's Convention at Chicago, 111., by
LCDR Wilson R. Cronenwett, USN,
Head, Motion Picture Branch, U.S. Naval
Photographic Center, Anacostia, D.C.,
and Dr. William M. Timmons, Educa-
tional Adviser, Naval Photographic Center.

could be used only for training a rela-
tively small number of men. Necessary
skills and knowledge in such highly
technical and complex fields as elec-
tronics and fire control also proved the
inadequacy of the apprentice system.
The untrained man could not learn
these complex skills and knowledge by
observation. He could work beside
the experienced man for many months
without learning more than the super-
ficial aspects of the work. Too much
was hidden from direct view, or there
was so much to view that one couldn't
interpret it.

The training film, along with other
aids and methods, has solved the train-
ing problem. It has many of the merits
of the apprentice system, while at the
same time permitting observation of
those things which are normally hidden
or which are cluttered up in a maze of
detail. It is equally useful for teaching
simple skills and techniques, and highly

July 1952 Journal of the SMPTE Vol. 59

complex and technical ones. More-
over, it can effectively and rapidly
teach many men simultaneously.

This was the need that had to be met
during World War II. It was a big
need and was not met all at once. The
program grew. In the summer of
1941 the staff to meet the need con-
sisted of one junior officer. By 1945
over one hundred officers were supervis-
ing the production of films. The Photo
Science Laboratory had its own staff of
writers, cameramen, editors, and tech-
nicians. There were about 30 training
aids libraries and about 70 officers advis-
ing on film utilization. By early 1945
over 1000 motion pictures had been
produced, as well as 2500 slide films.
Close to a million prints had been
distributed.

The films produced were good, bad,
and indifferent. A surprising number
were superior. All contributed to the
practical job of training many officers
and men in Navy skills and information.
That they were generally good is due
to a number of factors. The Navy
leaned heavily on many small com-
mercial producers who had developed
considerable know-how in producing
films for business and industry — prac-
tical films, often training films. The
officers recruited as project supervisors
came from two primary sources, the
film industry and education. They,
with the small commercial producers,
made Navy films what they were.

The project supervisors with their
diverse backgrounds were a source of
ideas, methods and procedures, as well
as of disagreements. They did not
solve all the problems of how to make
films that do the practical teaching job.
But out of the ferment of the war-time
group there came at least these results:

(1) A set of production procedures
were worked out. (These are still used.)

(2) Production control procedures
were developed. (These are still fol-
lowed, with refinements.)

(3) Emphasis was placed on a new
type of film, one designed to teach rather
than to entertain.

We knew what we wanted but we
did not know all the techniques of
making films that teach. We still do
not know, but we have made progress.

On the basis of this background, I
want to indicate how the Navy's film
needs are met today — what the pro-
gram is today. There are three basic
aspects to the program: production,
distribution and procurement.

Production

The overall responsibility for film
production in the Navy is in the hands
of the Bureau of Aeronautics, Photo-
graphic Division. Production super-
vision and control are delegated to the
U.S. Naval Photographic Center. All
training films are therefore produced
in their entirety at NPC or are pro-
duced commercially under the Center's
supervision. In either case they are
produced in close coordination with that
part of the Navy desiring the film.

Although we have the usual adminis-
trative personnel to keep the entire
program moving and an educational
specialist to insure that each film does
its intended teaching job, the key people
on any production are two in number.
One is the project supervisor, repre-
senting the Naval Photographic Center.
The other is the technical adviser
representing the Naval activity, school,
Bureau or fleet unit wanting the film.

The project supervisor acts as the
producer of his assigned projects. He
may be responsible for as many as twenty
projects at one time. He is responsible
for planning, scheduling and super-
vising all except purely technical aspects
of his projects from initial request to
final acceptance of the training film.
He must make sure that each of his films
does the intended teaching job, is right
as a motion picture, and is made within
the allotted budget. He must judge
the work of script writer, graphics

July 1952 Journal of the SMPTE Vol. 59

specialist, camera man, director, editor,
animators, sound technicians and proc-
essing technicians. Naturally he leans
on others to the extent needed, but his
is the final responsibility.

The technical adviser is an expert
in the content of the film. His basic
responsibility is to make sure that the
script and the resulting film are tech-
nically accurate and technically com-
plete in all details. In addition, he
must make sure that incidental things
shown are right, that approved safety
procedures are followed, that all clothing
is properly worn, that security regula-
tions are followed in what is shown,
and that even little things like haircuts
are strictly Navy.

The training film which these two
individuals, project supervisor and tech-
nical adviser, work on may be any one
of several types: motion picture, photo-
graphic report, public information film,
slide film or filmagraph. While this
classification may sound illogical, the
terms have grown in response to the
Navy situation. Some of the terms are
self-explanatory. Others need a word
of explanation. A motion picture is
any carefully planned, complete motion
picture production, in live action or
animation, designed for training pur-
poses. A film on How to Get Usable
Motion Picture Footage falls into this
category. A photographic report con-
sists of motion picture coverage of an
actual operation or activity put together
in the best way possible to give general
professional information to Naval per-
sonnel. A film showing an actual
amphibious landing, covered photo-
graphically as well as circumstances
permit, is a photographic report. A
public information film is any motion
picture telling the public about any
part of the Navy. The slide film needs
no definition. The filmagraph is essen-
tially the same as a slide film except
that the still pictures and the sound are
put on motion picture stock, and the
resulting film is projected on a standard

sound motion picture projector. With
careful planning, standard opticals and
the use of popped-on or dissolved-on
items or labels, camera trucks and
simple pans, the filmagraph becomes a
simulated motion picture. For certain
kinds of content, where continuous mo-
tion is unimportant or where motion
can be simulated by simple techniques,
the filmagraph is an excellent, low-cost
teaching film. We have used the
filmagraph, for example, to show how
to bend oak timbers and to explain the
Navy's part in our Revolutionary War.
In the Navy the filmagraph has largely
replaced the slide film.

During the fiscal year now ending, of
the films going into production 72%
were motion pictures for specific train-
ing purposes, 10% were photographic
reports for general training purposes,
less than 2% were public information
films, 16% were filmagraphs for specific
training purposes, and none were slide
films.

Thus, Navy production consists pri-
marily of films for training. These films
follow a general pattern of production.
At the outset someone in the Navy has
a training problem which he thinks
can be solved by a film. In consultation
with a representative of his parent Navy
Bureau and an educational specialist
from the Naval Photographic Center a
decision is made that a film will or will
not help solve the training problem.
If it is agreed that a training film is
desirable, they prepare a production
outline. The production outline is a
detailed analysis of who will see the
film, what the audience already knows,
what they should know or be able to
do after seeing the film, the content to
be included, the technical photographic
specifications and shooting locations.
In other words, the production outline
includes the basic specifications on which
the script and film will be based. Every
effort is made at this stage to insure
that only needed films are requested

Cronenwett and Timmoni: Navy Training Film Production

and that the requested film will be a
good teaching film.

The production outline is submitted
to the Navy Film Production Board
of Review. This board is made up of
officers representing the training and
fiscal parts of the Navy. They deter-
mine what training films are to be
produced, the priority and the basic
specifications for each film. For a
film to be approved, the need must be
justified, the plan must appear educa-
tionally sound and the project must
represent a wise expenditure of public
funds.

If the Navy Film Production Board of
Review approves the project, the Bureau
of Aeronautics assigns it to the Motion
Picture Branch of the Naval Photo-
graphic Center for production. It
becomes either an NPC production
done entirely with NPC facilities or an
NPC contract production done with the
assistance of a commercial studio. Pro-
ductions done entirely at the Center are
normally those of the highest security
classifications or those requiring shooting
on location or intermittent photography
that cannot be done efficiently by
commercial studios.

Regardless of how the film is to be
produced, the Photographic Center as-
signs the project to one of its twenty
project supervisors. The requesting part
of the Navy assigns a technical adviser.
These two individuals supervise the
preparation of a script. In all cases
where art or animation is to be included
in the film, the script includes a de-
tailed storyboard. The resulting script
must be more than technically correct.
•It must be capable of being produced at
a reasonable expenditure of time and
money. Expensive color is used only
if it will contribute to the teaching
quality of the film. The comparatively
inexpensive filmagraph is used rather
than the motion picture if the former
will accomplish the film purpose as
effectively. If a short film will do the
job, no padding out is permitted. The

script must be consistent with the speci-
fications laid down by the Navy Film
Production Board of Review, in accord
with governmental policy and in good
taste in all respects. It must lend
itself to becoming a good film from the
point of view of direction, photography,
editing and sound. Above all it must
be educationally valid.

It is on the educational side that
we are making perhaps our most out-
standing contribution. Emphasis on
educational effectiveness is placed at the
script stage. If the script is educa-
tionally sound and if the production
follows the script, there will be little
difficulty in making the resulting film
educationally sound.

We shall not discuss our educational
standards in detail here, but it may be
helpful to indicate a few of the general
principles followed. The scriot should
make the learner aware of what is
expected of him. The script should be
carefullv organized around the chief
instructional values to be gained from
the film, and this organization should
be prominent in the presentation.
The detailed development of every part
of the film should be slow and clear in
pictures and words, with primary em-
phasis on informative picturization.
The treatment should be consistent
with the film purpose and should gener-
ally be expository rather than telling a
story or hanging on "gimmicks." The
commentary should be simple, precise,
brief, direct, dignified and closely inte-
grated with the pictures. The intro-
duction should be no longer than
necessary to take the learners from
where they are in information to the
body of the film. The conclusion should
reinforce the chief learnings. Obviously,
the project supervisor must lean heavily
on education and cost experts to make
sure that he is meeting all his responsi-
bilities at the script stage. In the same
way the technical adviser must lean on
other experts on fine points of the film
content.

July 1952 Journal of the SMPTE Vol. 59

The script and story board must be
approved by the superiors of both the
project supervisor and the technical
adviser.

Then the project goes into production,
following the normal procedures of the
industry. Because emphasis in direct-
ing, photographing, processing, editing
and recording is on accomplishing the
film purpose with integrity and authen-
ticity, departures from the approved
master script are never made for reasons
of caprice, entertainment or aesthetics
but only when changes are mandatory
from a teaching point of view. The
standards set by the industry on the
technical aspects of photography, proc-
essing, sound and other film matters
are followed by the Navy and the
superiors of the project supervisor care-
fully check these aspects at interlock
and acceptance screenings.

Distribution

The training aid to meet a specific
training need has become a reality.
To move this physical film to the many
training schools, naval activities, reserve
schools and the fleet, is a prime re-
sponsibility of Naval Film Distribution.
Since the Navy is responsible for the
production of all motion pictures for
the Marine Corps, provision is also
made for distribution to that part of the
Naval Establishment. Operating under
the Training Division of the Bureau of
Naval Personnel, this activity has long
been aware of the production progress
of the motion picture. Following the
Acceptance Screening of the picture
at NPC, the film is screened before
specialists at the Bureau of Personnel.
These personnel have had pre-produc-
tion information concerning the specific
need for this particular training aid
and have had conferences with the
sponsoring Navy Bureau. The total
number of film copies needed to perform
the best training job is ascertained.
Copies of such a highly specialized film
as African Trypanosomiasis will not com-

pare with the need for copies of a film
on Small Boat Disaster Prevention. Nor-
mally, each major training film library
will have at least one copy of every film
made, and in the majority of instances,
they will have numerous copies available
to service the many users. With the
recall of many reservists and the de-
mothballing of ships, the major training
film libraries will have many of the
hundreds of copies made so that fleet
units will be able to carry on immediate
training with these aids. Within a
month following the Korean outbreak,
fleet demands swept the shelves of all
extra copies of training films. Since
the Navy film program was instituted,
over 1,300,000 prints of training films
have been distributed. The training
potential of these prints is undeniable.
To answer the question in your minds
as to actual printing procedures, the
work is divided between the printing
facilities at NPC and commercial firms
awarded printing contracts through
competitive bidding.

The Navy feels that its distribution
program must differ from present-day
commercial practices. Since a 16mm
print is relatively inexpensive, the
emphasis is on making sufficient prints
of a picture to insure that its information
can be quickly disseminated, be readily
available, and in such quantities that
it will therefore satisfy the original need
for the training medium. It is not
unusual for print requirements to exceed
300 copies before a script is written or a
camera grinds.

Procurement

This last of the three points deals
with procurement practices of scripts
and motion pictures not produced
directly on the NPC sound stage, or by
NPC crews.

Last year, over 100 motion pictures
were completed for the Navy and the
Marine Corps. Of these, 25% were
service-produced at or by NPC. The
remaining 75% were produced com-

Cronenwett and Timmons: Navy Training Film Production

mercially under our direct supervision,
as shown above.

Almost daily, independent producers,
large and small, self-styled professional
cameramen, and small photographic
facilities want to know whether they
can make Navy pictures, whether they
are large enough to produce for the
Navy, what equipment they must
buy to produce for the Navy, if the
Navy will underwrite an initial pro-
duction, and they ask a thousand other
questions that might be considered
laughable, were it not for the seriousness
of their intent.

Navy motion pictures have been
produced commercially by Hollywood's
biggest firms, and by smaller producers
in Chicago, Philadelphia, Atlanta, De-
troit, Pittsburgh, New York, St. Paul and
elsewhere.

There are six steps that must be taken
by a producer wishing to make films for
the Navy.

(1) In a letter in triplicate, addressed
to the Chief, Bureau of Aeronautics
(PH), Department of the Navy, Wash-
ington 25, D.C., give a resume of your
organization, including type and brief
history, and state whether you are a
corporation, a partnership, or sole
proprietor.

(2) State that you are interested in
Navy film production and the type you
consider yourself best suited to handle.
This information gives the procurement
officer a better understanding of your
capabilities and the kind of work on
which to give you an opportunity to bid.
If you are one of hundreds on a list,
it isn't very practicable to ask you to
bid on a film which will employ highly
specialized types of medical photog-
raphy, or other techniques in which
you are not experienced. If the film
is to be 100% animation, do you have
an animation stand? Neither is it
practicable, if you are located on the
West Coast, to ask you to bid on a
submarine film to be shot in New
London, Conn.

(3) List your key personnel and give
a brief outline of their experience in
motion picture work.

(4) State the major types of facilities
and equipment owned, or how made
available to your company. There are
no arbitrary rules about the size of your
studio, nor will the Navy look askance
at having sound recording done in a
studio established for that purpose.
However, if the major portion of your
equipment is not owned, you are in
effect not in the motion picture business.

(5) Enclose a balance sheet listing
your assets and liabilities. The in-
formation will be held in strict confidence.
Give the straight facts. The Navy's
procurement analysts aren't to be
fooled. The Navy does not pay in
advance and the Government cannot
sponsor you in business. The concern
is whether you have the capabilities to
complete an awarded contract. The
emphasis is upon financial "soundness."

(6) Forward samples of pictures re-
cently produced by your company,
preferably educational or training films.
The Navy wants to know what you can
produce now, not what you produced
several years ago.

The emphasis is on these basic factors:

(1) experience (and the kind of experience);

(2) key personnel and their experience;

(3) physical facilities in terms of equip-
ment owned; (4) financial stability:
(5) the films you have produced and for
whom; and (6) security clearance.

There are no geographical advantages,
except that certain kinds of physical
work naturally gravitate to the most
convenient qualified source. But it is
equally important to note, as all pro-
ducers would emphatically agree, that
national assignments involving con-
siderable distances and location work
have no such boundaries, that Eastern,
Midwestern or Western companies work
over a considerable geographical area.

The Navy takes considerable pride
in its past and present procurement
practices with commercial producers,

July 1952 Journal of the SMPTE Vol. 59

large and small. This association has
been singularly marked by a fine spirit
of mutual cooperation.

Conclusion

This has been a general view of the
Navy's training film production program.
It is a big program: 6091 films have
been produced since the program was
started back in 1941. It is an important
program: the films have helped train
thousands of officers and men. It has
made at least a small imprint on civilian
education and training: over 600 titles
have been released to the public through
the Office of Education, some of them
selling as many as 1000 prints. The
program owes much to the reserve
officers who got it under way. It also
owes much to the film industry. We are
constantly trying to make it better —
not for the sake of being better, but so
that through training films more men
can be trained better and faster to do
jobs that have to be done.

Supplement

The Naval Photographic Center's
film depository and its service to the
film and television industry are apparent
to everyone who is familiar with the
Navy's cooperation and assistance in
the production of such feature pictures
as Frogmen, Submarine Command, You're in
the Navy Now, the television documentary
serials Crusade in Europe and Crusade in
the Pacific, and in other current television
shows and weekly newsreels. The film
depository at NPC contains over 30
million feet of historical stock footage
shot by Navy and Marine cameramen.
In many instances there is duplicate
material from other services. Non-
classified sections of this storehouse of
film and certain other services are
available to commercial producers. The
Navy, with the other services, has ex-
tended military cooperation or has
collaborated on the production of com-
mercial motion pictures for both the-
atrical and television release. Included

under cooperation is the search for,
and use of, official stock motion picture
footage in connection with commercial
pictures.

The clearinghouse for all requests
for cooperation from any of the services,
including the use of Navy-owned stock
footage, is the Commercial Cooperation
Unit, Pictorial Branch, Office of Public
Information, Department of Defense.
The wait for such help is not as long as
the address mentioned, for the govern-
ment understands that motion pictures,
whether full-length features, documen-
taries or short subjects, and whether
intended for theatrical or television
release, are a vitally important and far-
reaching means of sustaining public
understanding of the military. The
Commercial Cooperation Unit is geared
to get applicants the help they need,
and coordinates it through the Office
of the Chief of Information — Depart-
ment of Navy, which handles all further
details. At this point, NPC enters the
picture. The time lapse is surprisingly
short. For instance, a request was
made and filled within 48 hours for eight
minutes of stock footage to accompany
the TV appearance of CDR Gray,
USN, on the program "We the People."
The Naval Photographic Center film
depository will arrange a convenient
time for you or your representative to
screen selected stock footage, or if the
requirement is small will choose the
material you need and forward it to you.

It is understandable that the amount
of cooperation for stock footage or other
services is directly proportional to the
reach or scope of the production and
its potential informational value. Re-
quests for small lots of stock footage are
filled as a public service. Either a
fine -grain or a Kodachrome printing
master is supplied. In the instances 01
stock footage for Hollywood major
productions, arrangements are made to
reimburse the Navy with a like amount
of raw stock.

Cronenwett and Timmons: Navy Training Film Production

It would be well to mention here that
an average of 80,000 ft of motion picture
negative was coming to NPC from
Navy sources all over the world each
month before the outbreak of the
Korean war. Since then, the shipments
of original unprocessed negative stock
has risen to 200,000 ft a month. In
every case where security permits, a
fine grain of selected footage of timely
public interest is sent by the Department
of Defense to the newsreel and television
pool in New York. Duplicate negatives
of this timely footage are then purchased
by production organizations from a
commercial printing laboratory in that
area.

Your initial request for cooperation
will bring a full set of instructions from
the Department of Defense. The neces-
sary, but small details, will not be given
here. The most important facet of this
situation is this consideration: if Navy
footage is required, your production
will be impracticable or impossible
without official cooperation from the
Navy. You will need to furnish a state-
ment of your intent to produce and
distribute for public consumption, a
feature or short subject motion picture
or television show based on some phase
of the Navy. Your script will be
included, and pertinent information as
to the type of assistance required, i.e.,
stock footage, sound effects, technical
advice, clearance to board Naval vessels
or aircraft, or to borrow military
equipment needed for authentic scenes,
or actions.

In any event, security must not be
compromised, the cooperation must not
interfere with private enterprise, it
must not interfere with military opera-
tions or the command concerned, and
it must not cost the taxpayer or the
government anything. An excellent il-
lustration of such cooperation was the
recent request by a major Hollywood
studio wishing to photograph aviation
activities aboard a carrier. No such
ship was immediately available for use

on the West Coast but the camera
crews were able to board a flattop on
its way to Korea and do their necessary
photography before the ship reached
Hawaii, at which point the commercial
crews departed.

Discussion

M. R. Klein (Director of Army Film Library
Services) : Does the Navy instructor use a
teaching technique in using the training
film prior to showing the film? And also
as a follow-up after the film is shown? In
other words, are pertinent questions about
the film prepared as part of the teaching
technique in using your film?

W. R. Cronenwett: If I might comment as
a former enlisted man, I saw a great many
training films before I got into my present
work. The Bureau of Personnel Training
Division strives in every way to prepare a
"package," so that the film or other
visual aid is not the sole teaching medium,
but exists as one of the teaching tools
with which the Navy instructor works.
We have made films for the trained and
untrained instructor, who then knows —
before he ever meets an audience — what
he should do, how to bone up, the questions
to ask, what questions he might be asked,
and the answers. The film, the instruc-
tor's booklet, the other visual aids, the
instructor — the human element — meld
to train the fleet as best we can. I hope
I've answered your question.

Howard Johnson (Federal Civil Defense
Administration): Referring back to the pro-
duction aspect of your paper, I think there
are three points that require re-emphasis —
three significant contributions of the Navy
training film program. A good many of
us will agree, I think, that the storyboard
concept of planning a film is important in
the documentary training film area;
secondly, that most training films are one
reel in length, which is important for
curriculum integration, important for
proper film utilization aboard ship or the
shore station; and thirdly, that most
Navy training films are documentary
training films, in the best sense.

I would like to have you comment
again on the emphasis of the storyboard
planning for film production and its value.

LCDR Cronenwett: We find that in
working with many people in the Navy

July 1952 Journal of the SMPTE Vol. 59

who do not have a film production concept
that the use of a storyboard, with the
script, will enable the requesting authority,
and others who will pass upon the film
before it gets to the fleet, to visualize the
final product. As to film length, we feel
that a film should be designed for a specific
need. That is, if it needs to be a 3£-
minute film, we'll make it ; if a 1 3-minute
film, we'll make that too. Too often a
contract might call for a two-reel picture,
and when 18^ minutes of film will do an
adequate job, the film editor will need-
lessly lengthen the scenes to fill the two-
reel requirement.

What was your third point, Mr. Johnson?

Mr. Johnson: Emphasis on the docu-
mentary ....

LCDR Croncnwett: Many of our films,
as you can well imagine, are documentary
in approach since many of them are
photographic reports. In other words,
we'll go out to cover an amphibious
landing as best we can, without pre-
planning, because you can't always know
what's going to happen. It would be as
though we had planned to kine the show
we saw on TV here this afternoon. Some-
thing invariably happens. May I say
here, with pardonable pride in behalf of
those people — officer and civilian — who
have made training films for the Navy
since 1942: twelve Navy films have won
16 national and international awards.
I think these awards are based upon
educationally sound, technically accurate,
and technically well made motion pictures.

Cronenwett sin4 Timmons: Navy Training Film Production

Nonsilver Photographic Processes

By THOMAS T. HILL

A number of nonsilver photographic, or light-sensitive systems such as those
based on diazo dyes, have been used or proposed for specialized purposes.
None of them, as yet, exhibits the sensitivity or the wide applicability of the
silver process. This survey of the current status of these systems will discuss
current limitations as well as possible future prospects with particular reference
to the field of motion picture engineering.

'EFINED BROADLY, photography is
a very widespread field. It includes
all those systems by which an image
can be made more or less permanent,
an image resulting from an exposure to
some type of light. Occasionally we see
mention of new systems of photography
and though they are often very promis-
ing, we are still working with the silver
system of photography. So, the ques-
tion arises, "Why haven't some of these
other possibilities come into use?"

This paper will review some of these
other possibilities, their advantages and
their disadvantages in comparison with
our current silver system, and discuss
what we are likely to hear from them
in the near future.

First, however, we must note that,
while we grumble about the short-
comings of the silver emulsions which
we now use, the necessity of processing
them in solutions and finally the neces-
sity of using them properly, they are

Presented on April 24, 1952, at the Society's
Convention at Chicago, 111., by Thomas
T. Hill, The Edwal Laboratories, Inc.,
Ringwood, 111.

really very versatile and set a high
mark of accomplishment against which
to compare the new possibilities. Ex-
amples of the wide versatility of silver-
salt photography are easy to find,
ranging from astronomical photography
to photomicrography.

A discussion such as this one develops
a new respect for the silver system, in
that it is applicable to so many aspects
of our work. On examination, we find
that many of these newer light-sensitive
systems are of narrow ranges of useful-
ness.

Photographic chemistry is but a
branch of photochemistry, which studies
all reactions caused by or accelerated
by exposure to light. Among the many
photochemical reactions are some which
appear to be bases of new photographic
systems, but which on further study are
either so insensitive or have so limited
an application that they are not really
practical.

Among the possible light-sensitive
systems of interest to us at present are
the following (some of these, of course,
are physical as well as chemical systems) :

July 1952 Journal of the SMPTE Vol. 59

diazo dyestuffs; diazo sulfonates; metal-
diazonium system; dye bleach color
systems; gelatin dichromate systems
(and similar ones used in the graphic
arts); thermography (such as the
Minnesota Mining system); light-sensi-
tive glasses (such as those of Corning);
differentially hardened plastics and resins
(such as bitumen, etc.); miscellaneous
metals and metal salts (including those
of lead, thallium, selenium, etc.); iron
(such as those in blueprints); electro-
photography (such as Xerography);
platinum and palladium compounds
(actually used in making prints from
silver-salt negatives) ; and mercury salts.

Some of these processes or systems
appeal to us because of either simplified
processing, adaptability to varied tem-
peratures, low costs or great stability
in the final product. But, when bal-
anced against the advantages of the silver
process, they have all, up to now, fallen
short, except for single specialized uses.

It is that aspect which will be dis-
cussed here in some detail. We should
know something of what we can expect
from these "new" systems and what we
should not expect from them. In some
cases, enthusiasm has been substituted
for results, and we have to use some cau-
tion in assessing the reported examples
of new proposals.

Evaluation of various systems:

Of course, not all of these nonsilver
systems are new; many of them have
been used for years for specific purposes.
One of the most used is that based on
the light-sensitivity of iron compounds
which form a blue-colored salt upon
exposure to light. We are all familiar
with the blueprint, and many of us
have used blueprint paper to make
prints from still-camera negatives. The
process, as you will recall, is very slow,
requiring strong artificial light, or
sunlight, and in most cases the papers
in use are designed for high contrast
rather than for continuous tone repro-
duction. As generally used, the results

are not as permanent as silver images,
although with proper treatment they
can be made quite satisfactory.1 But
such special treatment eliminates two
of the blueprint's advantages, low cost
and simple processing. On these bases,
together with the low sensitivity, we
can eliminate this system from our
consideration as a possible competitor
to a silver compound in actual motion
picture work.

In the field of plans and engineering
drawings, the diazo print2 is replacing
the blueprint since it is a positive method,
giving a positive copy of the original,
and having greater contrast. Properly
prepared, it is also more stable. Be-
cause of its ease and cheapness of
processing and the low cost of the
original material, the diazo system of
photography is more promising than
many others, and much effort has been
put into it to make it more useful, and
more of a competitor to the silver system.
However, it has some important dis-
advantages from our present viewpoint,
mainly very low sensitivity and a limited
tone range. For black-and-white photog-
raphy, the diazo system has another
disadvantage in that there is no true
dense opaque black available. The
best blacks, so far, in this field are
mixtures of dyes giving a very dark
color which appears black on an opaque-
base print, but does not have the density
of a silver material.

The low sensitivity here is the problem
which we meet again and again in
studying the various nonsilver systems.
In general, the advantage of the silver
system is that it can be sensitized (in
the meaning of that word used by
emulsion chemists). That is, by adding
small amounts of certain dyes and
organic compounds together with sulfur
compounds, the sensitivity of silver
salts to light, including now the use of
fluorescent materials, is greatly increased.
But there is another great difference.
In silver photography, a latent image
produced by a very small amount of

Thomas T. Hill: Nonsilver Photographic Processes

light is sufficient to give us the final
results. This is because the working
image is formed from that insignificant
latent image by chemical reactions
which themselves put energy into the
system. In the case of diazotype, this
is not the case, and all the energy needed
to form the image must come from
light energy. This is, of course, limited
by the quanta of light available. In
the case of the diazo system, which is
a positive process, the light destroys the
ability of the colorless dye precursor
to couple to form the colored dye.
Thus the areas receiving the most light,
of course, give the least color on develop-
ment, and those receiving no light
give the densest color. But the energy
necessary to make the change which
produces the image is a result of energy
applied to the system by the light,
which makes the exposure. The chemi-
cal reactions taking place in the coupling
reaction after exposure do not introduce
chemical energy in the way that a silver
photographic developer applies it.

Diazo materials have been experi-
mented with as print material for photo-
graphic uses,3 and even the simplicity
of processing has not completely offset
the low sensitivity and the short tone
scale. Its success here has been in
reproducing the sound track used in
optical methods of sound recording.4
Its ability to produce high resolution
has been given as a great advantage
here. However, the newer magnetic-
tape methods of sound recording appear
to be better at the present state of our
knowledge.

As an example of what has been done
with diazos, one fascinating attempt to
improve this material, especially in its
sensitivity, has been that worked out by
the Philips organization of Holland and
described in detail in the Journal.*
Here, the low cost of the diazo material
and its great resolving power are made
use of, and the lack of sensitivity is
partly overcome by combining with
metal systems of mercury or cadmium,

and by using silver and other materials
in the "development." However, tech-
nical difficulties have yet to be com-
pletely overcome, and the process has
not yet been put on the market. We
will not take time here to discuss it in
detail since it has already been well
described in our Journal, as well as in
other publications.4-5

A related system is that employing
the diazo sulfonates,2-6 which differ
from the diazo system in that they
produce a negative-type image such as
we are familiar with from silver salts.
The other interesting aspect of these
compounds is that some of them are
developable by the application of heat,7
rather than by chemical reactions of
separate developers. However, these
compounds do not appear to be as sensi-
tive even as the diazo compounds them-
selves, and there is great difficulty in
trying to make papers or film materials
with them which are stable enough to
store or ship.

Brief mention should be made here of
the dye-bleach color systems,8 such as
those used in such color photography
methods as the early types of Caspar
color and others, which have been
amply described in our own Journal
and corollary literature. Here again
we have the difficulty of sufficient sensi-
tivity for original taking-film, but the
materials have been applicable to making
prints from negatives produced by using
other processes.

Of course, several very old systems
that have been used for reproduction
purposes are those like the gelatin-
dichromate9 system, or its cousins, where-
in there is a differential hardening of a
gelatin or other colloidal layer by the
action of light, which affects the ink-
receptivity of the layer.9* These systems
are the mainstay of the printing trades
today and they are exceedingly useful
in many ways, but they have a low
sensitivity and require arc-light expo-
sures, as well as freshly coated material
prepared just before exposure. Recent

July 1952 Journal of the SMPTE Vol.59

attempts have been made, some success-
fully, to utilize diazo-type compounds
in printing-plate materials10 in order
to obtain presensitized plates which
can be prepared and stored for some
time before use. These still, however,
require strong light sources and long
exposures. All these systems require
the use of a "screen" in order to re-
produce tones, which limits their use-
fulness.

In somewhat the same field, fall the
various differentially hardened plastics
and resins,11 and the old methods
utilizing such materials as bitumen and
pitch. As a matter of fact, some of the
very old photographic processes antedat-
ing the daguerreotype utilized such
systems12; however, they required ex-
posures to sunlight in terms of hours,
and did not give a very stable result.

An interesting variation of this idea
is a recent report from a German ex-
perimenter13 of the fact that the use of a
tanning developer such as catechol, on
a silver halide emulsion in gelatin will
produce shadow detail in the gelatin
itself in areas beyond those which
receive the weakest silver image upon
development. It is proposed to make
use of this by dying the gelatin and
then washing away the unhardened
lesser-exposed areas with warm water,
leaving a silver image, together with
this dye-plus-gelatin image, which com-
bines to make a denser negative, espe-
cially in the very weak shadow regions.
This would, of course, require a special
type of emulsion and additional special
treatment which, though it appears to
be capable of greater sensitivity than
the silver methods normally used, re-
quires extra care and treatment in
processing which makes it difficult of
application.

Salts of various heavy metals such as
lead,14 thallium,15 selenium16 and many
others have been used to form photo-
graphic images, such as were also
formed in an experiment during the
late war by one military man who used

the familiar trinitrotoluene or TNT
to make a photographic image.17 He
did this by coating paper with a solution
of TNT, drying it and exposing it to
light. In all these cases the sensitivity
so far appears to be very low, and no
method of increasing the sensitivity has
yet been reported.

One rather surprising nonsilver sys-
tem has recently been proposed which
is brought to mind by the use just
mentioned for TNT. This is the use
of explosive materials to form an image
by the results of the explosion. In a
recent report the use of nitrogen tri-
iodide is described. This is a ticklish
material which many of us used to use
in schooldays for practical jokes; it
will explode with great noise when
slightly disturbed, even when tickled
with a feather. In this case, the light
falling on it through a lens is sufficient
to set off an explosion, and an image
is left on the support, burned in by the
explosion. 18

The light-sensitive glasses developed
by the Corning Glass Works19 are of
interest, especially as they will give
some colors as well as black-and-white
images, but they are not practical for
motion picture engineering use because
of the fragility of the base material,
the special processing (requiring very
high temperature fusing) and other
difficulties, which we understand also
include a low sensitivity. The colors
obtained are not "natural" colors as in
Kodachrome, etc.

On the other hand, quite interesting
advances have been made with various
processes of electro-photography, such
as have been developed at the Battelle
Memorial Institute in connection with
the work of Haloid Go. under the name
of Xerography.20 Further work on this
has been done at the Signal Corps
Engineering Laboratories (Squier Signal
Corps Laboratory) at Fort Monmouth,
N. J., and reported in the recent litera-
ture.21 They appear to have overcome
the early difficulties of poor tone-scale

Thomas T. Hill: Nonsilver Photographic Processes

reproduction, and we have seen portraits
made by this process which had fairly
good quality.

The process basically involves the
"sensitizing" of a prepared selenium
plate by giving it an electrostatic charge.
Upon exposure to light, in our case to
an image, the resistance of the plate
drops in the higher exposure regions,
so that the charge there is less. De-
velopment consists of dusting on a dry
powder which clings to the areas still
holding the most electrostatic charge.
This powder image may be fused to
permanence by heat, or transferred to
another paper support and then fused.
Three to five seconds in a photographic
dry mounting press will do the trick.
The plate itself can then be cleaned and
re-used for another picture. The great
advantage here is the speed of processing
and the fact that it is an all-dry system
without water solutions. However, the
manipulation by the operator including
the preparation of the plate just before
exposure, whether of selenium or of
phosphors22 (both of which systems are
used), is quite difficult and delicate,
and a high-tension electrical system is
necessary to utilize this method. It
gives a direct-positive result, and does
not as yet appear to be applicable to a
negative-to-positive system. However,
a great deal of work is being done on
it for the various applications such as
photocopy work, special Air Corps
cameras, and even for X-ray use,23 and
to prepare lithographic printing plates.24

Another interesting process announced
fairly recently, is that referred to as
thermography,26 exemplified by the heat
copying process, recently announced by
the Minnesota Mining & Mfg. Co. In
this process, called Thermofax, the
image is formed by an infrared or heat
exposure which melts a waxy material
where inked areas concentrate the heat,
and the resulting image on a special
paper is both a positive and a negative.
This may be rather confusing, but the
fact is that as a result of this exposure

you get a print on a semi-opaque paper
which by reflected light looks like a
positive, since the exposed areas are
darker than the chalky blue-white
background (of the example we saw).
However, when viewed by transmitted
light, those exposed areas become a
transparent light blue against an opaque
whitish-blue background, and form a
negative image which can be used to
make prints by usual contact printing
methods on silver-salt materials. This
appears to have interesting applications
for office photocopy use, and this is the
first commercial application being
worked on. However, it requires ex-
posure to heat, or infrared rather than
visible light rays. It does not appear
to have a great deal of tone range, and
it appears to be very slow, as with so
many of these nonsilver systems; there-
fore, as presently described, it does not
appear to have any application at all
for our present purposes.

Conclusions

Having now discussed and described
some of these proposed light-sensitive
systems, the question is, Where do we
go from here?

It would seem that each of these
systems, which we have so briefly
examined, has at least one great short-
coming in comparison to the silver-
salt process we are so familiar with.
They all appear to have a low sensi-
tivity to light. Many of them appear
to have a poor tone range, and some of
them seem to require even more compli-
cated processing techniques to produce
the final image.

It would therefore seem that, as pre-
sently developed, none of these systems
has any immediate direct application to
motion picture photography, that is in
preparing either the positive print or
the negative film from which the positive
is printed. There are a few cases, such
as the Philips diazonium system, which
appear to have some promise for
making prints. This is also true of

July 1952 Journal of the SMPTE Vol. 59

some of the dye-bleach color systems
such as early Caspar color. In a few
cases the low sensitivity is not so im-
portant. But where the sensitivity has
been even somewhat increased, the cost
of the material is no longer low, and
therefore such a system is less competitive
with the silver-salt process than it was
originally.

Of course, in auxiliary aspects of our
work, some of the nonsilver processes
can be used but not in a direct, motion-
picture-taking application.

But what of the future? Can some
of these processes come up to the overall
advantages of the silver process? A
close study of the literature in a number
of these cases, and first-hand experience
with a number of these processes in the
laboratory, indicate that they have
a long way to go before any of them
could successfully challenge silver for
more than a small part of silver's great
range of usefulness. For example, we
have had an opportunity to watch an
investigation recently of claims to a new
process by which the sensitivity of a
diazo dye process was to be increased
to equal that of silver materials. When
it was finally boiled down it was found
that the sensitization simply did not
work. Applied to textiles, this special
type of diazo process was quite practical,
but it required terrifically long ex-
posures or exposures to extremely bright
light at very close range, and it required
exposure of the material while wet. So,
another hopeful method of speeding up
one of the nonsilver processes went by
the board.

In general, our present conclusion
must be that none of these other proc-
esses is likely to become competitive
to the silver process in the near future,
for our purposes. In some specialized
fields, such as photocopy work, and other
cases where high exposure speed and
good tone range are not necessary, there
is great hope that some of these methods
will give results equal to that given by
silver emulsions at lower costs and with

simpler processing techniques, but with
the very high requirements of the motion
picture art, we of this group cannot
expect much from any of these "new"
systems for a long time to come.

Therefore our major efforts at present
should be expended on improving the
processing technique of the silver process
in order to simplify it, and lower the
cost. Some of these methods appear
to be very promising, such as the
stabilization techniques to replace the
fixing and washing stages of normal
silver processing. The use of higher
temperatures, spray processing pro-
cedures and other improvements in
this aspect, will decrease some of the
few disadvantages of our familiar and
very successful silver light-sensitive
process.
Bibliography

D. A. Spencer, Ed., Progress in Photography,
1940-1950, Focal Press, London and
New York, 1951.

M. M. Eder, History of Photography, trans-
lated by E. Epstean, Columbia Uni-
versity Press, New York, 1945.
K. H. Saunders, The Aromatic Diazo Com-
pounds and Their Technical Applications,
2nd ed., Edw. Arnold & Co., London,
1949.

J. Friedman, History of Color Photog-
raphy, American Photographic Pub-
lishing Co., Boston, 1942; and his
monthly columns in American Pho-
tography in the 1930's and 1940's.
Edward K. Kaprelian, "A survey of
photographic processes and materials,"
Phot. Eng., 7, No. 2: 42-55. (This
includes an extensive bibliography of
80 items.)

J. W. Mitchell, Ed., Fundamental Mecha-
nisms of Photographic Sensitivity, Butter-
worth's, London, 1951.
B. de Goster, "The principles and possi-
bilities of diazo-copying processes," /.
Documentation, 5: 1-11, June 1949.
S. C. Slifkin, "Status of developments in
the German diazotype reproduction
process," FIAT final Report No. 1082,
May 2, 1947; PB Report No. 78,256.
(These are published by agencies of
the U.S. Dept. of Commerce, Wash-
ington 25, B.C.)

Thomas T. Hill: Nonsilver Photographic Processes

References

1. C. A. Crowley and J. B. Mullen,
U.S. Pat. 2,317,521.

2. K. H. Saunders, The Aromatic Diazo
Compounds and Their Technical Applica-
tion, 2nd ed., Edw. Arnold & Co.,
London, 1949, pp. 363 ff.

3. A. M. Gheftel, "Ozaphane film and
the Cinelux projector," Jour. SMPE,
25: 358-360, Oct. 1935; A. M.
Sookne and C. G. Weber, "The
stability of the viscose type of ozaphane
photographic film," Jour. SMPE, 31:
611-618, Dec. 1938.

4. R. J. H. Alink, G. J. Dippel and K. J.
Keuning, "The metal diazonium sys-
tem for photographic reproductions,"
Jour. SMPTE, 54: 345-366, Mar.
1950. (This article was reprinted
from Philips Technical Rev., 9: 289-300,
1948.)

5. C. J. Dippel, "The metal diazonium
process," Phot. J., 90B: 34-41, Mar.-
Apr. 1950.

6. FIAT Final Reports, Nos. 528 and
813 (available from the U.S. Dept.
of Commerce, Office of Technical
Services, Washington 25, D.C.) and
BIOS Final Report No. 1480, p. 72
(available from British Information
Services, 30 Rockefeller Plaza, New
York 20, N.Y.).

7. FIAT Final Report No. 528, p. 6.

8. J. Friedman, History of Color Photog-
raphy, American Photographic Pub-
lishing Co., Boston, 1942, p. 502;
B. Caspar, U.S. Pat. 2,049,005; E. I.
DuPont de Nemours & Co., Brit. Pat.
592,679 (U.S.A., May 9, 1944).

9. (a) C. M. Willy, Practical Photolithog-
raphy, Pitman, London, 1940, es-
pecially pp. 1-3; (b) J. S. Mertle,
Process Photography and Platemaking,
G. Cramer Dry Plate Co., St. Louis,
Mo., 1946, especially pp. 133-137.

10. Robert C. Rossell, "Hi-speed process-
ing plate," NatL Lithographer, 56, No.
5: 40, 60, May 1949.

11. R. E. Liesgang, Z. wiss. Phot., 30:
156-157, 1931.

12. J. M. Eder, History of Photography, 1st
English translation by E. Epstean,
Columbia University Press, 1945, pp.
200 ff.

13. J. Rzymkowski, "A Method of In-
creasing Photographic Sensitivity by

Tanning Development," in Funda-
mental Mechanics of Photographic Sensi-
tivity, J. W. Mitchell, Ed., Butter-
worth's, London, 1951, p. 220.

14. A. Schoen, General Aniline & Film,
U.S. Pat. 2,414,839 and 2,504,593.

15. M. J. Harper and M. Ritchie, "Further
observations on latent image formation
in thallous bromide gelatin systems,"
Trans. Faraday Soc., 46: 641-645, Aug.
1950.

16. P. Selenyi, "Photography on se-
lenium," Nature, 767: 522, Apr. 1948;
also, G. Berraz and E. Virasaro,
Anales inst. invest, dent, y tecnol. (Univ.
nac. litoral, Santa Fe, Arg.}, 10/11, No.
17: 41-47, 1942.

17. W. Snelling, Plum Brook Ordnance
Works News, 1, No. 20: 1, 6, Nov. 1942.

18. J. Eggert, "Contribution to the Photo-
chemistry of Endothermic Com-
pounds," in Fundamental Mechanics of
Photographic Sensitivity, J. W. Mitchell,
Ed., Butter worth's, London, 1951,
pp. 220 ff.

19. R. Dalton, U.S. Pat. 2,326,012, 1943;
and 2,422,472, 1947; S. D. Stookey,
"Photosensitive glass, new photo-
graphic medium," Ind. Eng. Chem.,
41, No. 4: 856-861, Apr. 1949; W. H.
Armistead, Jr., and S. D. Stookey,
Canadian Pat. 442,272; 442,273;
and 442,274, Dec. 8, 1943.

20. C. F. Carlson, U.S. Pat. 2,221,776,
1940; 2,277,103, 1942; 2,297,691,
1942; and 2,357,809, 1944. See
also review of patents in this field by
Frank Smith, Phot. Eng., 2, No. 4:
258-259, 1951.

21. See review of patents in this field by
Frank Smith, Phot. Eng., 2, No. 4:
258-259, 1951.

22. R. E. Aitchison, "Preparation of
photoconducting cadmium sulphide,"
Nature, 167, No. 4255: 812-813, May
1951; also E. Wainer, "Phosphor
type photoconductive coatings for con-
tinuous tone electrostatic electrophotog-
raphy," Phot. Eng., 3, No. 1: 12-22,
1952.

23. R. C. McMaster, "New developments
in Xeroradiography," Non-Destr. Test-
ing, 10, No. 1: 8-25, Summer 1951.

24. L. E. Walkup, "Lithographic plates by
Xerography," Penrose Annual, 45: 134-
135, 1951.

July 1952 Journal of the SMPTE Vol. 59

25. F. CJrbach, "Thermography," Phot.
J., 90S, No. 4: 109-114, July 1950;
Thermojax, leaflet published by Minne-
sota Mining & Mfg. Co., St. Paul,
Minn.

Discussion

Wm. H. Ojfenhauser (Consultant): In
among some old film clips that I had a
number of years ago, there was a strip of
diazo process film that was printed in
France. The picture was Dreyfus. I lost
its history from that point on. I wonder
if you can tell us why the thing died or
why it might have started at all.

Thomas T. Hill: There was a lot of
promise in that process. Of course, the
diazo system is promising because you
have colors there and they thought they
could make use of it. Also it's nongelatin.
Actually the sensitive material is cast
right into the base, whether it's a celluloid
base or a cellophane base. Most of the
sound-track methods were on a cellophane
base like the Philips diazonium process.
One of the drawbacks was that you did
not have the dimensional stability and
the overall usefulness of your prints
running as many hundreds or thousands of
times as does a good print from material
we use now.

Another trouble was that these diazo
dyes were not as light stable, and after
projection a few dozen times the image
began to fade. It's very difficult to get
good fixing with diazo materials — so
nothing intensifies or darkens, and so that
the dyes do not fade. That seems to be
why that thing has fallen by the wayside
up to now. There's still enough promise,
I think, to continue with it, but it isn't as
good as was hoped for in the beginning.

Anon: Is there anything in the literature
that would indicate the problems of sound
recording on these nonsilver media?

Mr. Hill: That was one of the applica-
tions that the Philips diazonium process
was aimed at, because of its terrifically
high resolution — they thought they could
get a better sound track. But when I
talked to the men who had worked on it
in this country they told me that they
had found several things wrong with the
thing as developed in Holland and sent
it back for further research. One of the
troubles was that they spent all of their
time working on a material on a cello-

phane base. Because of the very thinness of
the material they could put a big reel of
film with sound track on a very small
area, but the people in this country
pointed out that the dimensional stability
of the cellophane wasn't up to what we're
used to in the motion picture industry
and it just simply wouldn't work for that
reason.

The other thing was, of course, the
mercury involved a health hazard which
they apparently hadn't realized. So it
has gone back to Holland for work with
the cadmium aspect of the system and Dr.
Jamieson of the Philips Laboratories in
Irvington-on-Hudson, New York, told
me recently that there's some promise
that they'll come back again with better
results for that specific purpose on sound
track.

Anon: So the summary is probably that
Eastman Kodak and du Pont and Ansco
can continue to make film for a little while?

Mr. Hill: For quite a while.

Anon: Until the magnetic boys catch
up with them.

Mr. Offenhauser: I'd like to bring in a
little more history at this point. Just
before World War II when I was with
John Maurer we were working with a
wide-range silver film master record
recording system for frequency modulation
broadcasting. We used Class A push-
pull, direct-positive recording on yellow-
dyed silver film with galvanometers that
peaked at 22 kc and with a film speed of
60 ft per min. The direct-positive was
printed in diazo material by Agfa-Ansco
at Binghamton.

We made prints on diazo material and
the objective at that time was to use the
prints from these records for FM stations
as transcription record material on account
of the fact that we found very low distortion
levels in the diazo prints from the silver
originals. I mention this as a matter of
history.

Mauro ^ambuto (Scalera Films, Rome,
Italy): One advantage of those diazo films
was that they scratched less in some aspects
of them. In connection with the sound-
track use of the diazo materials, I wish to
say that I also had some experience with
that particular film that was made in
France, and incidentally it was Dreyfus.
That was back in 1939. Now, there was
one major problem at the time due to the

Thomas T. Hill; Npnsilver Photographic Processes

fact that the diazo materials never seemed
to reach a very high density. So in this
particular instance, the most trouble they
had was with the signal-to-noise ratio. I
would like to know if in the new experi-
ments anything better has been achieved.

Mr. Hill: There has been a good deal
of work done on that aspect simply for
the office copying use of diazo on paper
in trying to get a better and more opaque
black, and I'm sure that some of those
things have given us combinations of dyes
which are better than we had, say, twelve
or thirteen years ago. It is that total
density that they're trying to improve,
but as with any of the dyes, where you have
a black dyestuff for cloth or any other
purpose, you really have a very dark color
rather than a true black. In the same way
with the diazo coupling, and as I mentioned
before, there is a faint fading going on so
that when you've got a total density
that's still a little less than you want and
then it starts to fade, you've still got
trouble. But I'm sure that some of the
dyes that have been worked out in the

past four or five years are much better
than they've had before.

Mr. Zjambuto: Could you give us any
figure as to the amount of signal-to-noise
ratio that was achieved?

Mr. Hill: In that case I can't. The
stuff I have seen has been on paper ma-
terials. We've been involved in the basic
chemicals rather than in the application,
so that we don't have that part of it going
through our lab. But we do have the
basic chemicals and their coupling to get
a black, black as possible on paper.

Mr. Offenhauser: As I remember it, we
had something like 60-db signal-to-noise
ratio and something less than 2% harmonic
distortion. The figures can be obtained,
I believe, from Andre Schoen in Bing-
hamton; he has the logs and test data.
We would never have contemplated using
these materials for FM transmission unless
the performance was that good or better.
We used blue-sensitive photocells with
matching dyes; these latter were peaked
in the same general spectral range. We
tried many dyes and cells experimentally;
the blue combination proved to have the
best performance at the time.

July 1952 Journal of the SMPTE Vol. 59

72d Semiannual Convention

Hotel Statler, Washington, D.C.
October 6-10

Wheels have been turning for the
Washington Convention ever since the
Editorial-Papers Committee Meeting at
Hollywood last October. In addition
to specific plans for last April's Chicago
Convention, general plans were laid for a
year ahead and Joe Aiken, Papers Com-
mittee Vice-Chairman for Washington,
D.C., was welcomed and was promised
cooperation from all present in his job as
Program Chairman.

The 72d Convention, even in its present,
embryonic form, is proving again the worth
of the practices and procedure worked out
over the past few years by Papers Com-
mittee Chairman Ed Seeley. It used to
be that the Papers Committee Chairman
organized the technical papers program
on his own primary responsibility and also
almost completely by his own efforts.
Not only was this a great burden on the
same individual twice a year but also it
was apparently less effective than having
someone in the convention city responsible
for the program; so Ed Seeley set up the
title and function of Program Chairman.
The Program Chairman is the Papers
Committee Vice-Chairman in the con-
vention city. General advice and carry-
over information go to the Program
Chairman from the Papers Committee
Chairman and also from the Program
Chairman of the previous convention.
The Society's headquarter's staff assists
only by trying to assure mutual under-
standing by all concerned and by channel-
ing suggestions which come from divers

members. The Editorial Vice-President
is responsible to the Society's Board of
Governors for the function of the Papers
Committee and so, also, for the technical
sessions of conventions. The Editorial
Vice-President's convention role, as most
recently exemplified by John Frayne, is
that of being helpful only when called upon
specifically and by using his special and
good offices to obtain special papers or
initiate plans for particular sessions.

Leads, suggestions, or finished papers
may originate with any interested person —
but all paper possibilities should be chan-
neled through a Papers Committee mem-
ber. The Papers Committee Vice-Chair-
man in the area should be kept informed
of the development. Papers Committee
members and vice-chairmen are responsible
for initiative in their respective companies
or areas.

For the Washington Convention, Joe
Aiken will also be Local Arrangements
Chairman, assisted by a roster of Wash-
ington folks who were nearly all appointed
at a meeting in Washington on May 29
when Convention Vice-President Bill
Kunzmann was in Washington to make
convention plans and commitments. The
list of those responsible for the many
duties and functions will be published in
the August Journal — but this does not
mean that there is no room for more
helpers or suggestions, particularly for
research, techniques or new products
manuscripts. These should preferably be
channeled through the Papers Committee
Vice-Chairman or member nearest you.
The complete Papers Committee is:

PAPERS COMMITTEE

Chairman: Edward S. Seeley, Altec Service, 161 Sixth Ave., New York 13

72d Convention Program Chairman: J. E. Aiken, 116 N. Galveston St., Arlington, Va.

Vice-Chairmen

For New York: W. H. Rivers, Eastman Kodak Co., 342 Madison Ave., New York 17

For Chicago: Geo. W. Colburn, 164 N. Wacker Dr., Chicago 6, 111.

For Los Angeles: F. G. Albin, Station KECA-TV, American Broadcasting Company

Television Center, Hollywood 27, Calif.

For Canada: G. G. Graham, National Film Board of Canada, John St., Ottawa, Canada
For International Symposium on High-Speed Photography: John H. Waddell, 850 Hudson St

Rochester 4, N.Y.

Papers Committee Members

D. Max Beard, Naval Ordnance Labora-
tory, White Oak, Silver Spring, Md.

A. C. Blaney, RCA Victor Div., 1560 N.
Vine St., Hollywood 28, Calif.

Richard Blount, General Electric Co.,
Nela Park, Cleveland, Ohio

R. P. Burns, Balaban & Katz, Great
States Theaters, 177 N. State St.,
Chicago 1, 111.

Philip Caldwell, American Broadcasting
Co., 6285 Sunset Blvd., Hollywood,
Calif.

F. O. Calvin, The Calvin Co., 1105 E.
Fifteenth St., Kansas City 6, Mo.

J. P. Corcoran, Twentieth Century-Fox
Film Corp., 10201 W. Pico Blvd.,
Beverly Hills, Calif.

P. M. Cowett, Dept. of the Navy, Bureau
of Ships, Washington 25, D.C.

G. R. Crane, Westrex Corp., 6601 Ro-
maine St., Hollywood 38, Calif.

E. W. D'Arcy, De Vry Corp., 1111 W.
Armitage Ave., Chicago 14, 111.

W. P. Button, 732 N. Edison St., Arlington

3, Va.
Farciot Edouart, Paramount Pictures

Corp., 5451 Marathon St., Hollywood

38, Calif.

F. L. Eich, Paramount Film Laboratory,
1546 Argyle Ave., Hollywood 28, Calif.

Charles Handley, National Carbon Div.,
841 E. Fourth PI., Los Angeles 13, Calif.

R. N. Harmon, Westinghouse Radio Sta-
tions, Inc., 1625 K St., N.W., Washing-
ton, D.C.

Scott Helt, Allen B. Du Mont Labs., Inc.,
2 Main Ave., Passaic, NJ.

C. E. Heppberger, National Carbon Div.,
230 N. Michigan Ave., Chicago 1, 111.

J. K. Hilliard, Altec Lansing Corp., 1161
N. Vine St., Hollywood 38, Calif.

L. Hughes, Hughes Sound Films, 21 S.
Downing St., Denver, Colo.

P. A. Jacobson, University of Washington,
Seattle, Wash.

William Kelley, Motion Picture Research
Council, 1421 N. Western Ave., Holly-
wood 27, Calif.

George Lewin, Signal Corps Photographic
Center, 25-11 35 St., Long Island City
1, N.Y.

E. C. Manderfeld, Mitchell Camera Corp.,
666 W. Harvard St., Glendale 4, Calif.

Glenn Matthews, Research Laboratory,
Eastman Kodak Co., Rochester 10, N.Y.

Pierre Mertz, Bell Telephone Labs., Inc.,
463 West St., New York 14

Harry Milholland, Allen B. Du Mont
Labs, Inc., 515 Madison Ave., New
York 22

W. J. Morlock, General Electric Co.,
Electronics Park, Syracuse, N.Y.

Herbert Pangborn, Columbia Broadcast-
ing System, Inc., 6121 Sunset Blvd.,
Hollywood 28, Calif.

B. D. Plakun, General Precision Labora-
tory, Inc., Pleasantville, N.Y.

Edward Schmidt, Reeves Soundcraft, 10
E. 52 St., New York 22

N. L. Simmons, Eastman Kodak Co.,
6706 Santa Monica Blvd., Hollywood
38, Calif.

S. P. Solow, Consolidated Film Industries,
Inc., 959 Seward St., Hollywood 38,
Calif.

J. G. Stott, Du-Art Film Laboratories,
245 W. 55 St., New York 19

W. L. Tesch, Radio Corporation of
America, RCA Victor Div., Front and
Cooper Sts., Camden, N.J.

S. R. Todd, Consulting Electrical Engi-
neer, 4711 Woodlawn Ave., Chicago, 111.

M. G. Townsley, Bell & Howell, 7100
McCormick Rd., Chicago 45, 111.

Three special sessions have long been
scheduled for the Washington Convention:
(1) an international symposium on high-
speed photography for as much as two full
days' sessions, some or all of them con-
current with other sessions; (2) a session
on magnetic striping of film; and (3) a
session on maintenance of 16mm equip-
ment. More details about these and other
sessions will be given in next month's
Journal. On August 6 all members will
be sent the Advance Notice of the Con-
vention. This is the usual folded postal
mailer which gives the schedule of sessions
and includes a tear-off postal for making
hotel reservations.

Engineering Activities

Status of Proposed Standards: In the past year or so quite a few proposed standards have
been published for trial and criticism. The status of these is outlined below to bring all
concerned up to date. — Henry Kogel, Staff Engineer.

Title

Date
pub.

Status

Cutting and Perforating Dimensions
for 35mm Motion Picture Film —
Alternate Standards for Either Posi-
tive or Negative Raw Stock

Emulsion and Sound Record Positions
in Camera for 1 6mm Sound Motion
Picture Film

Emulsion and Sound Record Positions
in Projector for Direct Front Pro-
jection of 16mm Sound Motion
Picture Film

Screen Brightness for 35mm Motion
Picture

A & B Windings of 16mm Raw Stock
Film with Perforations Along One
Edge

1 9/51 Approved by Standards Com-

mittee. Now out to letter
ballot of ASA Sectional
Committee PH22.

15 12/511 Further revisions have been

i proposed which are now
being considered by the

16 12/51] 16 and 8mm Committee.

.39

,75

5/52

1/51

Edge Number 16mm Motion Picture .83 1/51

Dimensions for Projection Lamps .84 2/51

Medium Prefocus Ring Double-
Contact Base-Up Type for 16mm

and 8mm Motion Picture Projectors
Dimensions for Projection Lamps .85 2/51

Medium Prefocus Base-Down Type

for 16mm and 8mm Motion Picture

Projectors
Enlargement Ratio for 16mm to .92 1/52

35mm Optical Printing

Trial period ends Aug. 15.
No Adverse comments re-
ceived as yet.

Adverse comments were re-
ceived. Several new drafts
have since been proposed
by 16 and 8mm Committee
to resolve the differences.
The latest is now going out
to letter ballot of the 16 and
8mm Committee.

Approved by PH22. Must
next be reviewed by
SMPTE Board of Gover-
nors for Sponsor approval.

Approved by Standards Com-
mittee. Now out to letter
ballot of ASA Sectional
Committee PH22.

SMPTE Officers and Committees: The roster of Society Officers and the
Committee Chairmen and Members were published in the April Journal.

Letters to the Editor

Re: Three-Dimensional Motion Picture Nomenclature

I have read with great interest Major
Bernier's article on "Three-Dimensional
Applications" which appeared in the
Jour. SMPTE, 56: 599-612, June 1951.

Major Bernier is to be congratulated on
his paper and also on the interesting ex-
perimental work which he and his unit
are conducting. The writer would, never-
theless, like to draw attention to a few
points in the paper in connection with
which there seems to be some confusion.

On page 599 in the Journal, reference is
made to "the composite or lenticulated
system," but just what Major Bernier is
endeavoring to convey by this terminology
is not clear. There are three main groups
of processes (embracing hundreds of
different modes of application) which
might conceivably, but should not, be
referred to in this way. These three groups
comprise: (1) integral processes, which
had their genesis in the idea conceived by
Gabriel Lippman and disclosed by him
in 1908 (Compt. rend., 746: 446-51); (2)
parallax stereogram processes, all of which
are derived from the principle described
in Frederic Ive's U.S. Pat. 725,567 (ap-
plication date, Sept. 25, 1902); and (3)
parallax panoramagram processes, which
depend on the principle of G. W. Kanolt,
described by him in his U.S. Pat. 1,260,682
(application date, Jan. 16, 1915).

The problems involved in producing
spherically lenticulated film as proposed
by Lippman were not solved during the
inventor's lifetime, but the earliest practical
process (for still photography) employing
a cylindrically lenticulated screen with
which the writer is acquainted was de-
scribed by Walter Hess in 1911 in his
Brit. Pat. 13,034.

The most important of Dr. Herbert
Ive's ideas relating to stereo kinematog-
raphy are those embodied in Brit. Pat.
348,118 (application date, Feb. 7, 1930)
and his corresponding U.S. application
(convention date, Feb. 9, 1929). Very
many other processes involving the use
of line or lenticular grids, for both still
and motion pictures, were evolved be-
tween 1911 and 1929.

In discussing, on page 601 of the Journal,
the various factors contributing to depth I
perception, Major Bernier has again
departed from accepted terminology, and
this may be confusing to some with limited
knowledge of the subject. For example,
factor No. 4, in Major Bernier's list should
read "Accommodation," not "Focus re-
action," and factor No. 6 should read
"Binocular vision," not "Stereoscopic
vision."

The word "stereoscopic" means (freely
translated from the Greek), of course,
"seeing solid" or, as we are accustomed
to say, three-dimensionally or stereoscopi-
cally. Accordingly, the term "stereoscopic
vision" applies to the net effect resulting
from the various contributory factors. In
compiling a "short list" of these factors,
it is, in the writer's opinion, difficult to
improve on the custom of dividing them
into two groups: (1) monocular factors;
and (2) binocular factors. In the first
group the chief factors are accommodation
and perspective, and in the second group
we have parallax and the faculty of con-
vergence. There are numerous subsidiary
factors, some of which are mentioned by
Major Bernier.

Referring to the comments in the second
paragraph of page 601, whilst it is, of
course, true that accommodation becomes
of decreasing importance with increasing
distance of the object, neither this fact
nor any other warrants definition of a
distance of 20 ft as "optical infinity."

The reasoning on the next paragraph
of the paper is based on a fallacy. It can
best be demonstrated experimentally that
the faculty of accommodation is stimulated
practically always when one is watching
projected motion pictures. The apparent
size of the image is no less important than
the distance of the screen in determining
the degree of stimulation. Let us suppose,
for example, that the film being projected
depicts an object moving toward or away
from the observer so that it is progressively
either increasing or decreasing in size.
If the object depicted is a familiar one,
and the apparent size of the image corre-

spends to a distance within the normal
range of accommodation, the eye will
attempt to accommodate for that distance.
This momentarily throws the screen out
of focus, so the eye then re-accommodates
\ for the plane of the screen. If, by that
time the image of the object — assumed
to be still moving — is at a different
"apparent" distance within the range of
accommodation, the eye will attempt to
accommodate for the new distance, there-
by again throwing the screen out of focus.
This cycle of events recurs with great
rapidity, and is sometimes the cause of
headaches amongst elderly cinema patrons,
whose ocular sensory organs and muscles
are, naturally, less responsive than those
of younger people.

With regard to the main subject dis-
cussed in Major Bernier's paper, namely,
the development of alternate-frame stereo
techniques, it is, perhaps, worth drawing
attention to the fact that the majority of
the basic problems involved were investi-
gated in England by the writer, Edwin
Wright and others several years ago.
Work on such processes has been aban-
doned by most workers in this country,
mainly owing to recognition of the fact
that the disadvantages resulting from
"time parallax" are inherent in all alter-
nate-frame systems.

There are several known methods of
overcoming the flicker problem, that
developed by Wright being as satisfactory
as any; the writer considers it preferable
to the use of the more complex Morgana
shuttle movement. A description of
Wright's method is given in the writer's
book, Stereoptics — An Introduction, Mac-
donald & Co. Ltd., London, 1951.

Major Bernier's comments concerning
the flicker problem are made somewhat
difficult to follow by this use of phrases
such as "a flicker frequency of 72 frames/
sec, or 36 frames /sec per eye," which do
not really convey what the author in-
tended, as the important matter is the
number of occultations per second rather
than the number of frames.

To understand the nature of the flicker
problem it is essential to appreciate that
with any projection system, whether stereo-
scopic or planoscopic, the rate of flicker
per second is equal to the number of
times per second that light is occulted from

each eye. Thus, in ordinary planoscopic
projection, the flicker rate is equal to the
product of the number of frames projected
per second and the number of blades in
the shutter. When projecting plano-
scopically at 16 frames per second, for
example, the flicker rate is 32 or 48 per
second according to whether a 2-blade or
3-blade shutter is employed. In neither
of these two cases is flicker perceptible
to the eye, so the term "flicker" is really
a misnomer in such instances. It is readily
demonstrable that the minimum rate of
occultation necessary to prevent the
occurrence of objectionable flicker is about
24 frames/sec, this rate being achieved
at a projection speed of 12 frames /sec
with a 2-blade shutter or 8 frames/sec
with a 3-blade shutter.

Now, with stereoscopic systems of the
type in question, light is occulted from
each eye every time a picture intended for
the other eye is projected. This means
that in addition to the faster, imperceptible
occultations produced by the shutter,
there occur occultations at a slower rate
numerically equal to one-half the number
of frames projected per second. Ac-
cordingly, in order to provide the necessary
minimum of 24 occultations per second for
each eye, a projection rate of 48 frames per
second must be adopted, regardless of the
number of blades in the shutter. As this
is generally impractical, it becomes neces-
sary to adopt some arrangement such as
those used by Wright and Major Bernier.
The writer ventures, nevertheless, to ex-
press the opinion that such arrangements
are not really worth while owing to the
facts that "time parallax" errors are still
present and that the apparatus is somewhat
complex. He would like, in conclusion,
to draw attention to the new single-film
polarized light process some particulars
of which are given in his paper "Stere-
oscopy in the Telekinema and in the
Future," which appeared in British Kine-
matography, 18, No. 6: 172-181, June 1951.
This would appear to be the most satis-
factory polarized light process so far
developed.

August 30, 1951 L. Dudley

Odeon Theatre
Kensington High St.
London, W. 8,
England

Reply to the Letter Above

The recent letter by Mr. L. Dudley,
director of the Laboratory, Odeon Theatre,
London, indicates his confusion in reading
my paper "Three-Dimensional Motion
Picture Applications," published in the
June 1951 issue of this Journal. I would
therefore like the opportunity to set forth
in more detail the explanation of certain
phraseology and certain technical aspects
with which Mr. Dudley was confused.

He points out that "there are three
main groups of processes, which might
conceivably, but should not be referred
to as the "composite or lenticulated sys-
tem," as I did on page 599 in the Journal.
Although he listed the three main groups,
he didn't give any indication of how that
type of three-dimensional photography
could intelligently be referred to. As I
see it, each of the groups has one thing in
common: namely, that a viewing device
on or near the eyes is not needed to vision
the three-dimensional results. Each de-
pends on a medium near the picture sur-
face to selectively direct the proper views
of the subject to their respective eyes.
To produce a stereoscopic vision in the
brain, this medium is dependent, in all
cases, on one basic fact, that the eyes
are displaced. Since the groups, as Mr.
Dudley refers to them, are therefore
more or less related, there should, in my
opinion, be some definite means of re-
ferring to them.

I could not find anything in the litera-
ture which seemed to suitably express
this phase of stereoscopy, and as a result
chose to refer to the latest refinements of
it as the "composite or lenticulated" sys-
tem. As to the source of the expression
"composite," it appears in the reference
book Medical Physics, edited by Otto
Glasser, Ph.D., Year Book Publishers,
Inc., Chicago, 1944-1950, on page 1326
in a treatise on three-dimensional photog-
raphy. The article under a paragraph
heading "Tri vision" reads "Early in 1941,
the Winnek Laboratory introduced a new
process of composite stereography, now
called "Trivision." Composite photog-
raphy, as defined in Webster's New Inter-
national Dictionary, means a photograph
or portrait made by a combination, or
blending of several distinct photographs,
either made one over the other, or made

on one print from a number of negatives."
This, in my opinion, comes very close to
describing the condition that exists in the
present picture emulsion of the French
"Portrait en Relief," the British "Deep
Pictures," or the American "Trivision,"
and other trade processes, all of which
stem from the pioneering efforts of H. E.
Ives (1902), Lippman (1908) and, of
course, Berthier (1896).

These refinements of which I speak,
consist in segregating and resolving (within
limits), by means of a lenticulated surface
in front of the emulsion, a continuous
changing view, or an infinite number of
views of the subject. Thus, when the
composite picture is viewed through the
same or an identical lenticulated surface,
left and right views are selectively pro-
jected to their respective eyes. Reasonable
freedom of movement of the viewing posi-
tion either laterally or perpendicularly
to the picture is possible, because any
two views of the composite, within the
angle of coverage of the lenticulation
formula employed, will always be a left
and right view of the subject, and will be
directed to the left and right eyes, re-
spectively.

The reason, thus, that I referred to this
phase of three-dimensional photography
as the "composite" or "lenticulated"
system is because, in my opinion, this
phraseology most adequately describes
this process of three-dimensional photog-
raphy which in turn has enjoyed limited
recent popularity as a result of a more
efficient combined use of these two basic
features.

I chose to use "Focus reaction" rather
than "accommodation" in listing my
interpretation of the basic factors of depth
perception, because it seemed to me that
this expression would be more easily
understood by the layman, rather than the
more technical expression "accommoda-
tion," used almost exclusively in ophthal-
mic practices. Also, I intended to imply
that it is not, in my opinion, the difference
in the character of the focus of objects
which notifies the brain of their relative
positions in space, but on the other hand
the reaction due to the tensing of the
ciliary muscles.

In connection with my use of "Stereo-
scopic vision" as the sixth factor, instead

of the commonly used phrase "Binocular
vision," I reasoned that it is possible to
use "two eyes" in certain cases, but not
to be able to see stereoscopically. For
example, the conventional binocular micro-
scope has two oculars, but only one ob-
jective; and thus when using such a
microscope binocularly, one does not see
stereoscopically. This is also true of some
binocular viewers for single Kodachrome
transparencies; also when viewing any
single photograph or painting binocularly
the subject matter cannot be seen stereo-
scopically. Thus it would seem that the
only requirement to actually view subject
matter stereoscopically is to change the
angle of convergence of the eyes for
different planes of depth.

We view present two-dimensional color
motion pictures on the screen with both
eyes, or binocularly, but we cannot see the
subject matter stereoscopically because of
the absence of the requirement to change
convergence for different planes of depth.
This would be a case where all the factors
that Mr. Dudley would like listed could
be activated, but we still could not see the
subject matter stereoscopically. This is
the reason I chose to use "Stereoscopic
vision" rather than "Binocular vision" as
the sixth factor of depth perception.

It seems to me that his reasoning "that
stereoscopic vision is the net result of the
various contributing factors" is based on
a fallacy. Stereoscopic vision is achieved
in the "Anti-Aircraft stereoscopic height
finder" without any of the contributing
factors Mr. Dudley mentions, except the
"faculty of convergence." The determi-
nation of the slant range of aircraft in this
case, depends solely on this factor, and as
I chose to say "Stereoscopic vision."

In connection with Mr. Dudley's objec-
tion to my use of the expression "Optical
infinity," and that I indicated that it
could be considered as 20 ft, I would
like to point out that this is a common
expression in the field of ophthalmology
and optometry, and to all American
trained optometrists the expression imme-
diately suggests 20 ft, since this theory for
many years has been and is being taught
in American colleges and universities (see
textbook Outline of Optometry by I. M.
Borish, page 36, Sec. 8 Al, or Physiological
Optics by W. D. 7oethout, 4th ed., Pro-

fessional Press, Inc., Chicago, 1947, page
38, paragraph titled "Principal Foci.")

The next paragraph of my paper,
contrary to Mr. Dudley's opinion, is based
on the fact that there is a direct relation-
ship between accommodation and con-
vergence. Namely, that when converged
at a certain distance, the eyes in a normal
individual will also automatically focus
for that distance and vice versa. This
relationship is thoroughly discussed on
pages 431 and 432 of A. C. Hardy and
F. H. Perrin's The Principles of Optics,
first edition, ninth impression, Camera
Craft Publishing, San Francisco, 1943.
Thus, if what Mr. Dudley says is true it
would seem to me that referring to the
examples he gives of a film depicting
objects moving toward or away from the
observer, that the eyes would also want
to change convergence. If they change
their convergence to follow the apparent
position of this moving object, the result
would be double imaging. This also
should occur "with great rapidity," but
I don't believe it does. I maintain, as
indicated in my paper, that as long as
subject matter in the three-dimensional
motion picture appears no closer than 6 or
8 ft from the observer, accommodation
errors will not result. I cannot agree
with Mr. Dudley on the cause of headaches
amongst some older people who go to
the movies, since it is common knowledge
in ophthalmic practice that they lose
their power of accommodation as a result
of progressive hardening of the crystalline
lens as they grow older. This would
indicate to me that as long as they were
wearing glasses corrected for the screen
distance, the subject matter on the screen
would remain always in focus. Therefore
it is interesting to note that when this be
the case, especially with three-dimensional
motion pictures, they will see subject
matter clearly even when required to
converge on three-dimensional screen ob-
jects, which could conceivably appear
as close as two or three feet in front of
their faces. As an added prediction,
they will quickly realize that for such a
phenomenon, they will not need to "peer"
through their "bifocals."

I prefer not to disclose as yet what im-
provements have been made in connection
with the alternate frame system. However,
I would like to assure Mr. Dudley that the

"time parallax" problem has been com-
pletely solved, and that the alternate
frame principle with the latest modifica-
tions shows promise, in my opinion, of
being the most all-around satisfactory
stereoscopic motion picture method to
date.

In regard to my use of the phrase "a
flicker frequency of 72 frames/sec, or 36
frames/sec per eye," I would like to clear
up Mr. Dudley's apparent confusion in
respect to the action of the Morgana
movement. This movement, I made
quite clear in my paper, actually transports
frames of film in and out of the film gate
at the rate of 72 frames/sec. This rate
of frame transport is, therefore, exactly
coincident with the shutter-blade rate,
and therefore is also identical to the total
"occultation" rate. Thus the right frames,
for example, are transported in and out
of the film at the rate of 36 frames /sec,
which also equals the "occultation" rate
for that eye, per second. Since, then, the
actual framing rate is also equal to the
flicker rate, I believe it reasonable to
express the flicker frequency in terms of
"frames per second." As I pointed out in
my paper, since every third transport
consists in moving a "frame backwards"
out of the gate, the net result is a "pro-
gression of the film through the projector
at standard sound speed."

Again I cannot agree with Mr. Dudley's
contention that "the minimum rate of
occultation necessary to prevent the
occurrence of objectionable flicker is
about 24 per second." If this were true
it would not be necessary to use a two-
bladed shutter in standard theater-type
projectors, which in turn doubles the
occultation rate with respect to the
"24/sec" frame rate.

When the film 3 D Motion Pictures was
screened at the SMPTE 1951 Spring Con-
vention, some may recall that there still
remained some flicker. This was due to
the comparatively slow flicker frequency of
36 frames/sec per eye. This frequency
was somewhat objectionable, and to bring
it up to present standards, improvements
had to be made. A new projector, which
will incorporate important changes will
be ready to demonstrate in the near future.

November 14, 1951

Robert V. Bernier, Major,
U.S.A.F.,

Hq. Wright Air Develop-
ment Center,
Box 7145, Area B,
Wright-Patterson AFB,
Dayton, Ohio

Obituary

Charles Ross died in June at the age of
63. He was President and sole owner of
Charles Ross, Inc., a business which he
started 30 years ago.

He began working for motion picture
studios in New York City when a boy,
one of his early employers having been
the Biograph Studios. He was an elec-
trician and he gradually built up stocks of
everything from cables to equipment
which eventually included every type of
lighting or grip equipment for motion
picture production.

He was educated in the New York public
schools and some time after he had begun
his business he and Pete Mole discovered
in mutual reminiscing that they had

grown up in the same New York City
neighborhood and gone to the same
schools without then being acquainted.
Charles Ross, Inc., has now for long been
sole eastern agents for Mole-Richardson
equipment. The firm's headquarters at
333 W. 52 St., New York 19, N.Y., is in
the same neighborhood where Mr. Ross
had offices and warehouse during his
decades in business.

Besides being an Active Member of this
Society, Charles Ross was a member of
Motion Picture Pioneers, Theatre Equip-
ment and Supply Manufacturers' Associa-
tion, Stage Employees' Local #1 of the
IATSE and Motion Picture Studio Me-
chanics Local #52 of the IATSE.

New Members

The following members have been added to the Society's rolls since those last published.
The designations of grades are the same as those used in the 1952 MEMBERSHIP DIRECTORY.
Honorary (H) Fellow (F) Active (M) Associate (A) Student (S)

Allen, James M., Cinematographer,
Sandia Corp. Mail: 223 La Merced
Ave., Albuquerque, N.M. (A)

Almond, W. Ritchie, Building and Main-
tenance of Technical Equipment,
Hungerford Laboratories, Inc. Mail:
358 Norwich Dr., West Hollywood,
Los Angeles 48, Calif. (A)

Althouse, Clinton R., Television-Radio
Technician and Engineer. Mail: 1540
N. Sierra Bonita Ave., Hollywood 46,
Calif. (A) t

Bailey, Marvin L., Film Editor, Sarra.
Mail: 5730 N. Ridge Ave., Chicago 40,
111. (M)

Barry, John W., Television Film Director,
Station WLTV. Mail: 227 Second
Ave., Decatur, Ga. (M)

Beaulieu, J. W. Roland, Supervisor, FM-
Transmitters, Canadian Broadcasting
Corp. Mail: 4505 Cote des .Neiges
Rd., Apt. 8, Montreal, Que., Canada.
(M)

Belok, Alfred, Color Consultant and
Technician, 112-20 Beach Channel Dr.,
Rockaway Park, L.I., N.Y. (A)

Bemis, Russell W., Designer, Dept. of
Architecture and Engineering, Uni-
versity of California at Los Angeles.
Mail: 8424 Lennox Ave., Van Nuys,
Calif. (A)

Bennett, Ralph S., Audio- Video Facilities
Engineer, National Broadcasting Co.
Mail: 51 Ellenton Ave., New Rochelle,
N.Y. (A)

Bennett, Lt. Wallace C., Motion Picture
Section, U.S. Air Force. Mail: 21539
W. Lake Rd., Rocky River, Ohio. (A)

Benton, Charles E., Jr., Photographic
Technologist, Assistant Chief, Photo-
graphic Technical Section, Naval Re-
search Laboratory. Mail: 4200 — 52
St., Decatur Heights, Bladensburg, Md.

Berryhill, Joseph L., Television Engineer,
Technical Supervisor, KRON-TV.
Mail: 143 Ridge Rd., San Anselmo,
Calif. (M)

Bevins, Ralph S., Assistant Sound Tech-
nician, Byron, Inc. Mail: 2709 S.
Wayne St., Arlington, Va. (A)

Bristol, Christopher, University of South-
ern California. Mail: 1184 W. 39
St., Los Angeles 37, Calif. (S)

Carlson, George M., Motion Picture Film
Developer, Byron, Inc. Mail: 137-35
St., N.E., Washington, D.C. (A)

Cobun, Charles C., Certified Public
Accountant, Senior Partner, Graves &
Cobun. Mail: 2504 W. 79 St., Ingle-
wood 4, Calif. (A)

Cohlan, Bernard F., Consulting Engineer,
719 Gayey Ave., Los Angeles 24. (M)

Crowell, F. E., Flight Test Photographer,
Boeing Airplane Co. Mail: 8426 —
22d S.W., Seattle 6, Wash. (A)

Daines, Eric Norman, Sound Recording
Engineer, British Lion Studio Co., Ltd.
Mail: 2 St. Mary's Rd., Ealing, W. 5,
London, England. (A)

Dauglash, William J., Sub-Manager and
Engineer, Westrex Co., Ltd. Mail:
675 Florentino Torres, Manila, Philip-
pines. (A)

De Poix, G., President, Bauchet et Cie.
Mail: Vert Bois, Rueil-Malmaison,
Seine et Oise, France. (A)

Eggers, Walter G., In Charge, Sensito-
metric Control, Mecca Film Labora-
tories, Inc. Mail: 235 E. 85 St., New
York 28, N.Y. (A)

Engel, Walter J., Executive, Motion Pic-
ture Cameraman, Walter Engel Studios,
Inc., 20 W. 47 St., New York 19. (M)

Esh, Raymond M., Wilding Picture Pro-
ductions Inc. Mail: 1664 Spruce Ave.,
Des Plaines, 111. (A)

Evans, A. E., Engineering Manager,
American Broadcasting Co. Mail: 2823
Kelly Ave., Hayward, Calif. (M)

Foley, Robert R., Electronics Engineer.
Bell & Howell Co. Mail: 508 S!
Humphrey Ave., Oak Park, 111. (A)

Gavin, Roy J., Sales Manager, Minnesota
Mining & Manufacturing Co., 3M Co..
900 Fauquier St., St. Paul 6, Minn.
(M)

Gell, Hugh Digby, Service Engineer and
Projectionist, Thomas O'Brien. Mail:
2 Henry St., KEW. E. 4, Melbourne,
Australia. (A)

Greig, Arthur W., Engineer, Mar. Broad-
casting Co. Mail: 13 Newton Ave.,
Halifax, Nova Scotia. (A)

Havill, Percy C., Projectionist, Beck
Theatre Corp. Mail: 918 Sunnyside
Ave., Chicago, 111. (A)

Hess, Stanley R., TV Manager, Wasser,
Kay & Phillips. Mail: 265 Ashland
Ave., Pittsburgh 28, Pa. (M)

Hilliard, Joseph Q., Chief, Optics Section,
Instrumentation Unit, Air Force Missile
Test Center. Mail: 266 Oleander
La., Eau Gallic, Fla. (M)

Holmes, Frank A., Color Film Duplicat-
ing, 7619 Sunset Blvd., Los Angeles
46, Calif. (A)

Horsley, David S., Director of Special
Photography, Universal-International
Pictures Co. Mail: 3846 Willowcrest,
North Hollywood, Calif. (M)

Hughes, Dale E., Film Producer, 186 E.
Center St., Marion, Ohio. (A)

Jaeger, Donald J., University of Southern
California. Mail: 2300£ Cahuenga
Blvd., Los Angeles, Calif. (S)

James, Stanley L., Projectionist and Sound
Technician, United Amusement Co.
Mail: 6 Carolina St., S., Hamilton,

' Ont., Canada. (A)

Jay son, Richard N., Color Motion Picture
Laboratory, Colorfilm, Inc. Mail: 20
Dogwood Ter., Livingston, NJ. (M)

Johnston, Andrew G., Motion Picture
Cameraman, Byron, Inc. Mail: 7325
Forest Rd., Hyattsville, Md. (A)

Kaplan, Neil K., University of Southern
California. Mail: 7760 Hollywood
Blvd., Apt. 311, Hollywood 46, Calif.
(S)

Keehn, Neal G., 16mm Film Production,
The Calvin Co. Mail: 112 W. 61
Ter., Kansas City 2, Mo. (A)

Kellum, Theron O., Re-recording Mixer,
RKO Radio Pictures, 780 N. Gower
St., Hollywood 38, Calif. (M)

Kezer, Charles F., Engineer, Fairchild
Recording Equipment Corp., 154 St.
& Seventh Ave., Whitestone, N.Y.
(A)

Kudar, John C., 1809f Las Palmas Ave.,
Hollywood 28, Calif. (A)

Langley, Frank P., Jr., Optical-Electrical
Engineer, Research Div., Philco Corp.
Mail: 708 Brooke Rd., North Hills,
Pa. (A)

Lewis, Herschell G., Radio-TV Pro-
ductions, Lewis & Clark, Inc., 1020 N.
Rush St., Chicago 11, 111. (A)

Liebers, Harold A., 307 Martense St.,
Brooklyn 26, N.Y. (A)

Lindsay, Leslie C., Audio and Television
Technician, Leslie C. Lindsay & Asso-
ciates. Mail: Steeles Corners, R.R.
#1, York Mills, Ont., Canada. (A)

Manohar, M. D., 41 Lokamanya Co-
operative Society, Bombay 16, India.
(M)

Mellott, Albert, University of Southern
California. Mail: 942 W. 34 St.,
Los Angeles 7, Calif. (S)

Meredith, John F., Producer, Ambassador
Films. Mail: 6648 Odell Ave., Chicago
31, 111. (A)

Moscaret, Joseph A., New York Uni-
versity. Mail: P.O. Box #54, Kew
Gardens 15, N.Y. (S)

Murray, Capt. John T., Motion Picture
Laboratory Supervisor, U.S. Air Force.
Mail: 5606 — 36 PL, Hyattsville, Md.
(A)

Nadeau, Arsene G., Chief Engineer,
Radio Station CHRC, Ltd. Mail: 11
St. Benoit St., Quebec, P. Que., Canada.
(A)

O'Brien, Robert H., Motion Pictures and
Television, United Paramount Theatres,
Inc., 1501 Broadway, New York 18.
N.Y. (M)

O'Toole, Russel, Sound Engineer, RCA
Service Co. Mail: 1321 Spear, Logans-
port, Ind. (A)

Paney, Harry E., Director, Photographic
Dept., Moody Bible Institute, 820 N.
La Salle St., Chicago 10, 111. (A)

Potter, Stannard M., Assistant Project
Engineer, Pratt & Whitney Aircraft,
Experimental Test 2, East Hartford,
Conn. (M)

Quinn, J. T., Chief Engineer, Wired
Broadcasting & Television, Rediffusion,
Inc., 1085 Beaver Hall Hill, Montreal,
Que., Canada. (M)

Rector, Eugene, Projectionist, Fox Mid-
west Theatres. Mail: 309 Crawford,
Ft. Scott, Kan. (M)

Robinson, Thomas J., Motion Picture
Photographer, Naval Research Labora-
tory. Mail: 3529 S. Utah St., Apt.
B-l, Arlington, Va. (A)

Rogers, Ralph L., Motion Picture Camera-
man, Baptist Sunday School Board.
Mail: 161 Eighth Ave., N., Nashville
3, Tenn. (A)

Roggenburg, Stanley L., Jr., Chemist,
E. I. du Pont de Nemours & Co., Inc.
Mail: 621 Ocean Ter., Staten Island 1,
N.Y. (A)

Salter, Victor M., Physicist, E. I. du Pont
de Nemours & Co., Inc. Mail: 31
Spring Ter., Red Bank, NJ. (M)

Schneider, Joseph, University of Southern
California. Mail: 1255 N. Sycamore
Ave., Hollywood 38, Calif. (S)

Sheldon, E. E., Physician, 490 West
End Ave., New York, N.Y. (A)

Sherman, Alan E., Illinois Institute of
Technology. Mail: 3254 S. Michigan
Ave., Chicago 16, 111. (S)

Shino, J. S., Electronics Laboratory Tech-
nician, Miltstark, Ltd. Mail: 48 W.
Lynn Ave., Toronto 6, Ont., Canada.
(A)

Siegel, Reuben S., Chemist, Signal Corps
Photographic Center. Mail: 737 E.
48 St., Brooklyn 3, N.Y. (A)

Slay maker, Frank H., Chief Sound Equip-
ment Engineer, Stromberg-Carlson Co
Mail: 1225 Clifford Ave., Rochester,
N.Y. (M)

Smith, Wallace T., Field Test Super-
visor, Sandia Corp. Mail: Ventana
Grande, Sandoval, N.M. (M)

Sorey, Lt. J. H., Head, Motion Picture
Processing Div., U.S. Naval Photo-
graphic Center, Naval Air Station,
Anacostia 20, D.C. (M)

Spruill, Dudley, Motion Picture Tech-
nician, Byron, Inc. Mail: 9601 Page
Ave., Bethesda, Md. (A)

Stalling*, Peyton M., Director, The Calvin
Co., 1105 E. 15 St., Kansas City, Mo.
(M)

Strickland, C. Louie, General Manager,
Strickland Film Co. Mail: 2592 Christ-
mas La., N.E., Atlanta 6, Ga. (A)

Takahash, Tom H., Photographer, Sandia
Corp. Mail: 631 W. McKnight, Albu-
querque, N.M. (A)

Tyner, H. P., Sound Engineer, RCA
Service Co. Mail: 1907 McKinney
Ave., Dallas, Tex. (A)

Valentino, Thomas J., General Manager,
Thomas J. Valentino, Inc., 150 W.
46 St., New York 36, N.Y. (M)

Varnum, [ennison, Sound Technician,
Radio Station KLAC. Mail: 1618
Tulare Ave., Burbank, Calif. (A)

Ver Halen, C. J., Jr., Publisher, Ver
Halen Publishing Co., 1159 N. Highland
Ave., Beverly Hills, Calif. (M)

Wagner, Richard J., Sound Technician,
Paramount Pictures Corp. Mail: 5661
Lemon Grove, Hollywood 38, Calif.
(A)

Wallace, Sj?t. Melvin, U.S. Army. Mail:
870 E. 170 St., New York 59, N.Y. (A)

Weiner, James R., Chief Engineer, Rem-
ington Rand, Inc., Eckert-Mauchly
Div., 2300 W. Allegheny Ave., Phila-
delphia, Pa. (A)

Wetzel, W. W., Technical Director,
Minnesota Mining & Manufacturing
Co. Mail: 725 Ridge St., St. Paul,
Minn. (M)

Wieder, Harold, Optical Engineer, Radio
Corporation of America, RCA Labora-
tories Div., Princeton, N.J. (A)

Wooten, Eugene W., Studio Relations,
Cinecolor Corp. Mail: 1331 Monaco
Dr., Pacific Palisades, Calif. (M)

Yuskaitis, Robert J., Owner, Eagle
Laboratory, 1732 N. Orchard St.,
Chicago 54, 111. (A)

CHANGES IN GRADE

Atkinson, R. B., (A) to (M)
Beard, D. M., (A) to (M)
Bernard, H., (S) to (A)
Blaney, Dorothy, (A) to (M)
Flory, John, (A) to (M)
Pfahler, R. A., (A) to (M)
Riley, L. W., (A) to (M)

Book Reviews

Proceedings of the National
Electronics Conference, Vol. 7

Published (1951) by National Electronics
Conference, Inc., 852 E. 83 St., Chicago
19, 111. 736 pp. incl. numerous charts,
diagrams and tables. 6 X 9 in. Price

$5.00.

This volume consists of the papers
presented at the seventh annual National
Electronics Conference held in Chicago
in the fall of 1951. The topics presented
cover just about the entire field of modern
electronics as can be seen by the subsequent
listing of subjects, and are extremely timely
to anyone working in the field. Your
reviewer found at least a dozen papers
that had direct bearing on immediate
problems.

The subjects covered include servo
theory, electron tubes, information theory,
audio systems, signal detection, com-
ponents, high-frequency measurements and

propagation, computers, magnetic ampli-
fiers, circuit analysis, industrial electronics,
television, and medical applications.

The editors of the volume are to be
commended for a fine job in taking the
numerous papers from different authors
on various topics and organizing them so
as to maintain continuity, especially in
style. This represents a continuation of
the good work done in the previous volumes
of this series.

The book is printed clearly and the
illustrations are very legible.

This well prepared and edited volume of
the Conference papers will serve either as
a well reported summary to those who were
unable to attend the meeting, or as a
convenient reference volume for those
who were there. It would be very de-
sirable if other major conferences would
publish similar proceedings. — H. L £agor,
General Precision Laboratory, Inc., Pleas-
antville, N.Y.

Professional Training
of Film Technicians

By Jean Lods. Published (1951) by
UNESCO, Paris. Distributed in U.S.A.
by: Columbia Univ. Press, 2960 Broad-
way, New York 27, N.Y. 155 pp. 8f X
5i in. Price $1.00.

A valuable addition to the Press, Film
and Radio Series of studies sponsored by
the United Nations Educational, Scientific
and Cultural Organization, this brochure
surveys a field whose importance has
only recently been recognized in this
country.

Its author is a distinguished French
film director, cofounder and Deputy
Director-General of the Institut des Hautes
Etudes Cinematographiques, a Government-
subsidized postgraduate school devoted
to the teaching of film aesthetics and
crafts.

In the ten countries investigated, states
Mr. Lods, "professional training is directly
conditioned ... by the situation, organiza-
tion and tendencies of the national film
industry." The latter, he finds, is divided
into three main types, depending on the
degree of government control.

This control may vary considerably,
but the author points out the universally
admitted fact that "the quality of national
film production is a matter of concern to
the entire country." Therefore, national
prestige is closely related to the competence
of film technicians and their professional
training.

In this respect, the high standards of
the French Institut can be judged by the
following question asked at the competitive
entrance examination for art directors:
"Voltaire's 'smile' is often mentioned.
Define and analyze this smile on the basis
of Candide. Relate it to a frame of mind
generally characteristic of the 18th cen-
tury."— George L. George, Screen Directors
Guild, 133 E. 40 St., New York 16, N.Y.

Fluorescent Lighting

By W. Elenbaas, J. Funke, Th. Hehen-
kamp, L. C. Kalff, A. A. Kruithof, J. L.
Ouweltjes, L. M. C. Touw, D. Ver-
meulen and R. Van Der Veen. Edited
by C. Zwikker. Published (1952) by
N. V. Philips' Gloeilampenfabrieken, Eind-

hoven, Netherlands. Distributed in U.S.A.
by Elsevier Press, Inc., 402 Lovett Blvd.,
Houston 6, Tex. i-x + 244 pp. + 4 pp.
index. 180 illus. + 23 photos. 6X9
in. Price $6.25.

The book reviews the scientific funda-
mentals of the design and operations of
fluorescent lamps and accessory equip-
ment, in terms of types and sizes used in
Europe. Chapters on fixtures and fluo-
rescent lighting applications are likewise a
report of European practice.

The section on color and color renditions
is a good summary of the fundamental
technology involved. The spectral data
on fluorescent sources, however, are based
on lamps manufactured in the Nether-
lands. Motion picture and television
engineers will find the book a convenient
way to compare European practice with
U.S. practice as reported in books and
periodicals published in this country. —
C. L. Amick, Lamp Div., General Electric
Co., Nela Park, Cleveland 12, Ohio.

The Recording and Reproduction
of Sound (2d ed.)

By Oliver Read. Published (1952) by
Howard W. Sams & Co., Indianapolis 1,
Ind. i-xv + 708 pp. + 70 pp. appendix +
10 pp. index. 708 illus. 6 X 9 in. Price

$7.95.

This volume contains a large amount of
information which should be of interest to
audio hobbyists and engineers in audio and
related fields. The sections on disc
recording and reproducing systems are
quite complete and magnetic recording
is also covered in considerable detail,
although no mention is made of recording
on "stripe" tracks on 8mm or 16mm films.
Photographic recording is barely men-
tioned. Public address amplifiers and
sound systems are treated at some length,
as are microphones and loudspeakers.

Much space is given to reprints of
manufacturer's bulletins, which may be
of interest to those using the particular
equipment described. The NARTB Disc
and Magnetic Recording Standards are
reproduced in full and numerous tables
and glossaries add to the usefulness of this
enlarged edition. — Clyde R. Keith, 5 North
Ter., Maple wood, N.J.

SMPTE Lapel Pins

The Society will have available for mailing after September 15, 1952, its gold and blue
enamel lapel pin, with a screw back. The pin is a ^-in. reproduction of the Society
bol — the film, sprocket and television tube — which appears on the Journal cover.
The price of the pin is $4.00, including Federal Tax; in New York City, add 3%
tax.

Positions Wanted

Photographic Chemist: 3 yr. experience black-and-white and color film laboratory
practice and quality control. Familiar with all commercial color processes and sensi-
tometry. Have conducted research in new processing methods. Position desired in
research or development on new products and processes. Will relocate. Write M-52,
c/o Lichtig, 3758 Tenth Ave., New York 34, N.Y.

Production, TV or Motion Picture: NYU BA in motion picture and TV production;
participated in productions as director and unit mgr; experience as motion picture
sensitometrist ; at present motion picture negative assembler and cutter; worked swing
shift while attending college; licensed 35mm projectionist; single, 29, veteran, resume
on request; go anywhere. Harold Bernard, 560 Eastern Pkwy, Brooklyn 25, N.Y.

Meetings

72nd Semiannual Convention of the SMPTE, Oct. 6-10, Hotel Statler,

Washington, D. C.

Other Societies

University Film Producers Association, Annual Meeting, Aug. 11-15, Syracuse Univer-
sity, Syracuse, N. Y.

Photographic Society of America, Annual Convention, Aug. 12-16, Hotel New Yorker,

New York

American Institute of Electrical Engineers, Pacific General Meeting, Aug. 19-22, Hotel

Westward Ho, Phoenix, Ariz.

International Society of Photogrammetry, Conference, Sept. 4-13, Hotel Shoreham,

Washington, D.C.

American Standards Association, Third National Standardization Conference, Sept.

8-10, Museum of Science and Industry, Chicago, 111.

Illuminating Engineering Society, National Technical Conference, Sept. 8-12, Edge-
water Beach Hotel, Chicago, 111.

Biological Photographic Association, Annual Meeting, Sept. 10-12, Hotel New Yorker,

New York

National Electronics Conference, Annual Meeting, Sept. 29-Oct. 1, Sherman Hotel,

Chicago, 111.

Optical Society of America, Oct. 9-11, Hotel Statler, Boston, Mass.

American Institute of Electrical Engineers, Fall General Meeting, Oct. 13-17, New

Orleans, La.
American Standards Association, Annual Meeting, Nov. 19, Waldorf-Astoria, New York

Motion pictures in color depend on the engineers' knowledge of the "Principles of
Color Sensitometry." A 72-page article bearing that title and prepared by the Color
Sensitometry Committee appeared in the Journal for June 1950. Attractive reprint
copies may be purchased for SI. 00.

New Products

Further information about these items can be obtained direct from the addresses given.
As in the case of technical papers, the Society is not responsible for manufacturers' state-
ments, and publication of these items does not constitute endorsement of the products.

Eidophor large-screen, color-television projection equipment: (1) Eidophor pro-
jector; (2) projection light beam hood; (3) color wheel; (4) auxiliary services (vacuum
pump, thermostat, and system for Eidophor cooling); (5) projection lamp (Ventarc-
type) ; and (6) television receiver circuits.

Eidophor large-screen, color-television
projection equipment has been installed
in the 20th Century-Fox Film Corp.
motion picture theater at 444 W. 56th
St., New York City, with demonstrations
for the press and invited public beginning
on June 25. A 30-min program of great
variety and color was originated and
transmitted from the sound stages of
Movietonews at W. 54 St. and Tenth Ave.

- Journal readers may recall the article
by E. Labin in the April 1950 Journal
when the Eidophor was described as
occupying two floors. Work toward the
Eidophor was described as early as 1941
by Hugo Thiemann and by Prof. Fritz
Fischer who directed the project until
his death in 1948. The Eidophor was
developed at the Polytechnical Institute
of Zurich, Switzerland, and was brought
to this country in part through the efforts
of Dr. Edgar Gretener A.G. of Zurich,
and by Dr. Thiemann who was on hand to

answer questions during the demonstra-
tions at Twentieth Century-Fox.

The present Eidophor projector is about
the size, weight and shape of a standard
motion picture projector. The Eidophor
has a Ventarc-type projection lamp
which was demonstrated at the Society's
Convention at Chicago in 1950 and
described in the October 1950 Journal.
The Columbia Broadcasting System's field-
sequential color process has been combined
with the Eidophor black-and-white equip-
ment. The CBS system was completely
described in, among other places, the
October 1951 Journal by Goldmark,
Christensen and Reeves.

Converting the original black-and-white
Swiss system to the color demonstrated
and getting the present model developed
and installed has been under the direction
of Earl I. Sponable, with notable assistance
from Hubert J. Schlafly, Lorin D. Grignon
and William F. Jordan.

Op timum Exposure of Sound Tracks
on Kodachrome Films

By ROBERT C. LOVIGK

Low-distortion sound tracks on Kodachrome films can be obtained with any
conventional exposure method. The best possible sound reproduction re-
quires exposure with light of color quality which correlates the speeds of the
individual emulsions when developed to silver sulfide rather than to dyes.
Poor sound quality in the past has often been the result of the.failure to recog-
nize the critical color quality requirement of the light which exposes the
sound-track portion of the film.

.ODACHROME Duplicating Color Film,
Type 5265 is a 16mm, reversal film de-
signed to be printed from color positives
on Kodachrome Films, Daylight Type
(5263), Type A (5264), and Kodachrome
Commercial Film (5268). The sound-
track deposit is silver sulfide. The sound-
track record is printed from silver posi-
tives prepared according to long-stand-
ing recommendations.

The sound process for Kodachrome
films consists of three basic steps. First,
the silver halides which were exposed in
the sound-track printer are developed to
a silver negative image. Second, thesilver
halide which remains is converted to silver
sulfide. Third, the negative silver is dis-
solved, leaving a reversal silver sulfide
image.

There are many complicating factors

Presented on April 24, 1952, at the Society's
Convention at Chicago, 111., by Robert C.
Lovick, Color Control Div., Eastman
Kodak Co., Rochester 4, N. Y.

in this basically simple process. For
example, the necessity of confining the
sound developer to the sound-track area
within small tolerances precludes the
use of agitation to aid in securing uniform
development.

Recent studies have shown that a large
part of the stain level of Kodachrome
sound records results from conversion of
some of the negative silver to silver sul-
fide. A modified developer which con-
verts a much smaller part of the negative
silver to silver sulfide is now being used.
There is a small improvement of signal-
to-noise ratio which is the result of the
increased useful transmission range. The
sensitometric effect of the sound de-
veloper modification is shown in Fig. 1.

Standardized Printing Methods

Printing to obtain the best possible
sound tracks on Kodachrome films re-
quires consideration of three facts.
First, the exposures are made on a multi-
layer film. Second, the three emulsion

August 1952 Journal of the SMPTE Vol. 59

I ,.0

0.5

.OLD TYPE

Sulfide Developer

MODIFIED^
Sulfide Developer^

LOG E
Fig. 1. Sensitometric effect of modified silver sulfide developer.

layers are sensitized to respond princi-
pally to three different colors of light.
Third, the speed relationships of the
layers are determined by the charac-
teristics desired for the dye formation for
pictures while sound-track development
converts the halides in all layers to silver
sulfide, a much different material.

Sound tracks on Kodachrome films
are usually printed using a conventional
sound printer with adjustments of the
printer lamp current to obtain a partic-
ular density. Changing the printer
lamp current results in the simultaneous
change of both the intensity and the color
quality of the light source. Since the
efficiency of different optical systems
varies considerably, and since many dif-
ferent types of lamps and heat absorbers
are in use, it is almost impossible to give
any information, such as a filter balance,
which can be applied without further
extensive tests on the particular equip-
ment involved.

Standardizing the light source for
sound-track printing requires very little
additional control work for most labora-
tories and makes possible the use of print-

ing recommendations without extensive
tests. If conventional distortion tests
can be made, there is still a considerable
saving of time and film because an ex-
cellent starting place is available for ad-
justing the exposure balance for partic-
ular equipment. Should emulsion
changes become necessary or desirable,
the extent of filter-pack modification
could be specified, reducing appreciably
the need of additional time- and film-
consuming tests.

A fixed color temperature of 2900 K
for a tungsten source is suggested be-
cause it is well within the rating of most
lamps and because experience has indi-
cated that more than enough light is
available on almost any printer. Heat-
absorbing glasses may greatly modify the
spectral energy distribution of the light
source. Heat-absorbing glasses should
be Pittsburgh 2043, 2 mm thick or an
equivalent filter. Adjustments of in-
tensity are made by neutral density
filters or diaphragms or both, depending
on the particular printer. The final ad-
justment of color quality is made with
Kodak Color Compensating Filters, but

August 1952 Journal of the SMPTE Vol. 59

0.4 0.5 0.6 0.7

DENSITY (of 8OOm//) OF UNMODULATED, UNBIASED AREA

0.8

Fig. 2. Intel-modulation. Unfiltered light of 2900 K tungsten source.

these filters are not part of the standard
source.

Kodak Color Compensating Filters
are gelatin niters and should be protected
from heat as much as possible. Heat-
absorbing glasses should be between the
light source and the filters and physically
separated as much as possible. Addi-
tional air-cooling of the filters is desirable
and may be absolutely required in some
printers.

The color compensating filters are a
necessary part of the filter pack for print-
ing sound on Kodachrome films. The
capabilities of printed Kodachrome film
for sound reproduction are much better
than previous investigators1-2 have re-
ported, primarily because so little at-
tention was paid to the color quality of
?the light used in exposing the sound
track. The color quality must coordinate
the speeds of the three layers or the best
sound quality will not be obtained.

Determination of Exposure Conditions
for Optimum Sound Quality

Distortion of variable-density prints
was determined by the intermodulation

method3 using conditions prescribed by
American Standard Z22.51. The nega-
tives employed were sensitometrically
normal negatives suitable for printing on
black-and-white release positive film.
A negative on Eastman Fine Grain Sound
Recording Film, Type 5373 was exposed
and processed for a gamma of 0.55 and
density of 0.55. This negative was
printed on Eastman Fine Grain Release
Positive Film, Type 7302 and processed
to a density of 0.55 and gamma of 2.50.

Variable-area distortion was deter-
mined by the cross-modulation test4 with
conditions prescribed by American Stand-
ard Z22.52. This standard designates a
4000-cycle carrier frequency amplitude-
modulated at 400 cycles/sec. The nega-
tives used were prepared on Eastman
Fine Grain Sound Recording Film,
Type 5372, with a gamma of 3.65 and
total diffuse visual density of 2.98. The
negatives were printed onto Eastman
Fine Grain Release Positive Film, Type
7302 to a gamma of 2.48 and density of
2.0.

A Western Electric RA-1100B Densi-
tometer was used for all density measure-

Robert C. Lovick: Sound Tracks on Kodachrome

0.4 0.5 0.6 0.7 0.8

DENSITY (at 600m//) OF UNMODULATED, UNBIASED AREA

Fig. 3. Intel-modulation. Filtered light of 2900 K tungsten source.

0.4 0.5 0.6 0.7 0.8

DENSITY (at 800m//) OF UNMODULATED. UNBIASED AREA

Fig. 4. Intel-modulation. Filtered light of 2900 K tungsten source
using stronger filters in the printing beam than shown in Fig. 3.

August 1952 Journal of the SMPTE Vol. 59

merits. A visual sensitivity characteris-
tic was used for all black-and-white
materials. The instrument was con-
verted to provide diffuse density measure-
ments at 800 m/i for densitometry of the
silver sulfide deposit on the Kodachrome
films.5

Low-distortion sound records on Koda-
chrome films can be obtained with any
conventional exposure method. The
quality of sound reproduction which can
be obtained is controlled by the color
quality of the light which exposes the
film in the sound printer.

The intermodulation curve shown in
Fig. 2 was obtained by measurements of
Kodachrome Duplicating Color Film,
Type 5265. This curve resulted from
exposure with the standard light source
previously mentioned but without addi-
tional color-compensating filters. The
only variable in this exposure was the
intensity of the printing light. A com-
mon error has been to assume, after
obtaining such a curve, that this repre-
sents the best that could be expected from
printed sound tracks on Kodachrome
film.

The series of intermodulation curves
in Fig. 3 were obtained from measure-
ments of Kodachrome film which had
been exposed to different color qualities
of light. The curve marked 30Y shows
per cent intermodulation for film ex-
posed to the standard 2900 K source
with a GG-30 Yellow filter in the printing
beam. Intensity changes were made
with carbon-deposit, neutral-density
niters.

The intermodulation curves shown in
Fig. 4 were obtained from measurements
of film which had been exposed using
stronger filters in the printing beam.
The curve obtained by printing with the
standard source plus Kodak Color Com-
pensating Filters equal to CC-70 Yellow
resulted in an intermodulation level of
4%. This low level of distortion was
obtained at a density at 800 rmi of 0.6
(diffuse visual density of 1.4). This is

the same density for which the minimum
in Fig. 2 was 19%.

One of the most important facts to
remember in judging sound-track quality
is that density has no significance what-
ever unless the color quality of the ex-
posing light is rigidly specified. Exami-
nation of Figs. 2, 3 and 4 clearly indicates
that merely obtaining a particular den-
sity on the Kodachrome film does not
guarantee quality.

The effects of small variations of color
quality are shown in Fig. 5. The curve
marked TOY + 20Y shows per cent inter-
modulation for film exposed to the 2900
K tungsten source with filters equal to
CC-90 Yellow. The series of color bal-
ances indicates that the color quality
is reasonably critical and also that the
low distortion is not the result of con-
finement of the image to any one layer.

The choice of an optimum balance for
variable-area track is less obvious be-
cause the cross-modulation product is at
least 40 db below the 400-cycle reference
level for a considerable range of color
balances. Additional considerations gov-
erning the choice of color balance for
exposing variable-area records are volume
level, signal-to-noise ratio, frequency re-
sponse, and exposure latitude. The
cross-modulation curves of Fig. 6 show
that the best color balance for variable
density, obtained with a CC-70Y filter
in the printing beam, is not the most
desirable balance for the exposure of
variable-area records. In this case the
CC-30M balance provides low distortion
with the highest usable volume level.
Again, density alone is not an indication
that the film has been properly exposed.

Conclusions

The color quality of the light which
exposes the film in the sound-track
printer controls the potential quality of
sound reproduction which may be ob-
tained from Kodachrome sound tracks.
Density alone is not sufficient to guaran-
tee that the color film has been properly

Robert C. Lovick: Sound Tracks on Kodachrome

uj 10

TOY + 20Y

TOY + 20C,

\ V

TOY + 20 M

TOY + 20R

/TOY + 206

+20B

0.4 0.5 0.6 0.7 0.8

DENSITY (ot 800m?) OF UNMODULATED, UNBIASED AREA

Fig. 5. Intel-modulation. Effects of small filter changes
from optimum variable-density balance.

O.I 0.2 0.3

DENSITY (ot 800m;/) OF CLEAR AREA

Fig. 6. Cross modulation. Comparison of best variable-area balance
with best variable-density balance.

August 1952 Journal of the SMPTE VoL 59

exposed. Density is only significant
when the color quality of the exposing
light is rigidly specified.

References

1. James A. Larsen, "Improved Koda-
chrome sound quality with supersonic
bias technique," Jour. SMPTE, 57:
60-62, July 1951.

2. John G. Frayne, "Electrical printing,"
Jour. SMPTE, 55: 590-604, Dec. 1950.

3. John G. Frayne and R. R. Scoville,
"Analysis and measurement of distor-
tion in variable-density recording,"
Jour. SMPE, 32: 648-673, June 1939.

4. J. O. Baker and D. H. Robinson,
"Modulated high-frequency recording as
a means of determining conditions for
optimal processing," Jour. SMPE, 30:
3-17, Jan. 1938.

5. R. G. Lovick, "Densitometry of silver
sulfide sound tracks," Jour. SMPTE, 59:
89-93, Aug. 1952.

Discussion

Anon: I'd like to ask the color temperature
and the type of photocell used in the play-
back on all of your test curves?

Mr. Lovick: The color temperature of the
lamp used in the reproducer was 2800 K.
It does make a difference. We use an un-
filtered Type 868 phototube.

Anon: It's a cesium cell?

Mr. Lovick: It's a cesium surface with an
S-l response.

H. R. Kossman (Gamer aflex Corp.} : I
would like to know a little more about the
filter for the sound printer. Is it a glass
filter you propose to use there?

Mr. Lovick: No, we're proposing to use
the Kodak Color Compensating Filters.
They are gelatin filters. You have to cool
these filters if they're tightly enclosed in
some printers, particularly in contact
printers. You don't have too much trouble
in printers such as the Bell & Howell
Model J.

Mr. Kossman: You know, we have rather
confined space there. Of course, they have
a blower system. . . .

Mr. Lovick: I realize that in many print-
ers there is quite a confined space. How-
ever, you cannot get good sound reproduc-
tion unless you make some provision for
using filters of this type to adjust the printer

light to the color quality that will give you
the best results.

Mr. Kossman: I notice that some of the
labs are using an ultraviolet filter.

Mr. Lovick: The ultraviolet filter gives
poorer results than you can expect from the
color-compensating type of filter. It also
takes considerably more light.

F. P. Herrnfeld (Herrnfeld Engineering)'.
You mentioned a 2-mm heat-absorbing
glass. Which one do you use?

Mr. Lovick: We use the Pittsburgh 2043.

Mr. Herrnfeld: Have you investigated
single-layer exposures?

Mr. Lovick: Yes, single-layer and double-
layer exposures. It's necessary to use pre-
flash techniques in order to avoid unmodu-
lated silver sulfide density in the other
layers. There's some improvement possible
for variable-density records particularly in
the exposure latitude. We don't lower the
minimum distortion but gain in latitude by
using a Wratten No. 29 filter to preflash the
bottom layer. There's no particular value
in trying to remove the middle layer of the
film. You get improved latitude at the ex-
pense of the signal-to-noise ratio.

George Lewin (Signal Corps Photographic
Center) : Will you tell us how this new
Kodachrome is going to be distinguished
from the present type?

Mr. Lovick: I believe the last of the old
Kodachrome emulsion is 5265-953. The
new films are number 1 or later.

Mr. Lewin: It will not be necessary to
order it specially?

Mr. Lovick: No.

Mr. Lewin: As time progresses, we'll
start getting the new type?

Mr. Lovick: The new type will be sup-
plied as rapidly as possible.

Mr. Herrnfeld: In your test, how do these
filters compare with the emulsion pack you
use for picture printing?

Mr. Lovick: The filter pack for picture
printing is a composite pack consisting of
some cyan, magenta and yellow filters. I
believe basically it's about 30 cyan, 30
magenta and 10 yellow. That's based
again on the 2900 K source that's recom-
mended for Kodachrome picture printing.

Mr. Herrnfeld: Have tests been made us-
ing the picture printing filter pack to print
the sound track?

Robert C. Lovick: Sound Tracks on Kodachrome

Mr. Lovick: The results are poorer than
those obtained with a properly color-
compensated sound exposure. The filter
pack that is used for printing pictures is
still almost a neutral pack, as far as that
2900 K source is concerned. There are
simply enough additional filters available
so that you can remove some to adjust the
color quality.

Mr. Herrnfeld: What was the filter pack
you mentioned? I mean approximately,
is it minus the yellow? The reason I am
asking is that I have made extensive tests
on other products and I have found that if
you get a good gray curve from your film,
in other words that the three emulsions
give you approximately the same gamma.

that is where we had the best processing
quality of sound films.

Mr. Lovick: That isn't necessarily true.
Each emulsion was designed for a particular
dye, irrespective of the amount of halides
necessary to get that dye. If you convert
those halides to silver sulfide instead of the
dye, the curve shapes are no longer similar
to what they were for the dye deposits.
There's no reason to believe that they'd
be similar. The speeds, too, might be quite
different. Suppose that you have to have
one and one-half times more halides avail-
able for the yellow layer than for the other
layers in order to get sufficient yellow dye
density. When converted to silver sulfide,
you would have that much additional con-
trast in that particular layer.

August 1952 Journal of the SMPTE Vol. 59

Densitometry of Silver Sulfide
Sound Tracks

By ROBERT C. LOVICK

Silver sulfide deposits have spectral density characteristics which tend to
make densitometry less reliable than density measurements of silver deposits.
Interference filters may be useful in restricting the bandwidth of response of
electronic densitometers so that densitometry of silver sulfide deposits will
have increased significance.

A HE SOUND TRACK on Kodachrome
film and other multilayer, reversal, color
films is commonly a deposit of silver
sulfide. Silver sulfide images are used
because no satisfactory solution has yet
been obtained to the problem of pro-
ducing a good silver image in the sound
track area and pictures free of silver in
the adjacent area.

The curves of Fig. 1 show density as
a function of wavelength for a silver
deposit on 16mm Eastman Fine Grain
Release Positive Film, Type 7302, and
for a reversal silver sulfide deposit on
Kodachrome Duplicating Color Film,
Type 5265. Physical densitometers
usually have maximum sensitivity in
the visual region at about 525 m/z. In
this wavelength region, the major
errors in the measurement of the density
of photographically deposited silver are
the result of the geometry of the instru-
ment. Differences in spectral response
of the receptor have practically no
effect on the calibration of the densitom-

Presented on April 24, 1952, at the Society's
Convention at Chicago, 111., by Robert
C. Lovick, Color Control Div., Eastman
Kodak Co., Rochester 4, N.Y.

eter. The accuracy of density deter-
mination may be adequately stated for
silver deposits. There is a tendency to
assume that the same reliability applies
to silver sulfide deposits.

The density of silver is minimum at
525 mju and increases moderately with
wavelength. The density of silver sulfide
varies much more with wavelength.
Assuming equal densities at a wave-
length of 800 mju, the slope of the spectral
density curve for silver sulfide is over
six times greater than the slope of the
curve for a silver deposit.

The density of the silver deposit
measured at 800 mju is 14% greater
than the density at 525 mju. The density
of the silver sulfide deposit measured at
800 mju is only 40% of the density at
525 m/i. Consequently, silver sulfide
sound tracks are visually denser than the
density effective in a reproducer with
a phototube having an S-l response.
As a result, reversal silver sulfide sound
tracks are often seriously overexposed
in attempts to give them the appearance
of silver sound tracks.

Measurements of sound tracks to
obtain indications of the density effec-
tive in a reproducer require that heat-

August 1952 Journal of the SMPTE Vol. 59

400

600 800

WAVELENGTH (millimicrons)

Fig. 1. Spectral density of silver deposits on Type 7302
and silver sulfide deposit on Type 5265.

1000

3.0

RMA Wavelength
Tolerance for

STANDARD S- I

EQUAL ENERGY

RESPONSE

400 600 800

WAV E L E N G TH (millimicrons)
Fig. 2. Standard S-l Phototube response.

1000

August 1952 Journal of the SMPTE Vol. 59

absorbers and other filters be removed
from the optics of the densitometer and
that the S-4 phototube be replaced
with a phototube having an S-l response.

Wavelength Tolerances

A standard, equal energy response
curve of a phototube with an S-l re-
sponse is shown in Fig. 2. The peak
sensitivity of a standard tube occurs at
800 m/z. Such phototubes were not
designed or ever intended for precise
photometric measurements. As a con-
sequence of their general purpose design,
wavelength tolerance limits of ±100
m/x have been established for the peak
sensitivity. These limits are entirely
satisfactory for their general purpose
service but can produce large differences
in the measured density of silver sulfide
sound tracks.

For the spectrophotometric curve of
silver sulfide shown and the maximum
and minimum wavelength tolerances for
peak sensitivity of the phototube, it has
been computed that the measured
density of the sample would be 0.68
and 1.3 respectively. The potential
error due to wavelength tolerance alone
for peak sensitivity of the phototube is
±30%. On a practical basis, this
error seems to be about ±10%.

Color Temperature Effect

The output of the phototube is the
product of the equal energy response
and the relative energy of the light
source at every wavelength. The curves
of Fig. 3 show the product of the stand-
ard response and the energy of tungsten
sources at 2500 K and 3000 K.1 Of
course, some densitometers may have
light sources with higher or lower color
temperatures than these, but this varia-
tion can introduce a significant error
in the densitometry of silver sulfide
deposits. If a standard S-l phototube
is placed in a densitometer and the color
temperature of the light source is changed
from 2500 K to 3000 K, the measured
density of this sample will change from

0.90 to 1.02. This is a density dis-
crepancy of ±6%.

Variations in Spectral Sensitivity

Another cause of differences in meas-
urements is the effect of different spectral
sensitivity for tubes having peak sensi-
tivities at the same wavelength. From
a small group of tubes having peak
sensitivity at the same wavelength, it
appears that this potential error is of
the order of ±3 or 4%, possibly larger.

These sources of error are important
because they are quite large and yet
may be overlooked in the estimate of
reliability of densitometry. The tend-
ency is to assume that because measure-
ments on a silver deposit in the visual
region indicate an accuracy of 1 or 2%,
that measurements on the silver sulfide
deposit are of the same order of re-
liability.

Measurements With Densitometers
Having Visual Response

Measurements of silver sulfide sound
track densities by densitometers with
phototubes having an S-4 response or
by visual instruments are much more
affected by the variation of density with
wavelength than are measurements with
instruments having phototubes with S-l
response. Density measurements, in the
visual region, of the silver sulfide de-
posits are more sensitive in detecting
density variations than are measure-
ments at 800 mju, but they are consider-
ably less precise. In addition, sound
tracks on Kodachrome films have some
unwanted magenta dye present which,
although virtually unseen by the usual
reproducer phototube, will contribute
significantly to the visual density
measurement. Visual density measure-
ments may, therefore, show variations
which in no way affect sound reproduc-
tion. The significance of visual measure-
ments is further reduced by the possi-
bility that as less silver sulfide is formed,
more magenta dye will be formed, and
although the visual density measure-

Robert C. Lovick: Densitometry of Sulfide Tracks

S-l RESPONSE
AT 3000 °K

-I RESPONSE
AT 2500° K

600 800

WAVELENGTH (millim icrons )

1000

Fig. 3. Effect of tungsten light source color temperature change.

3.0

1. Interference Filter

2. Interference Filter plus Wratten 38A

400

600 800

WAVELENGTH (millim icrons)

1000

Fig. 4. Spectral density characteristic of one type
of interference filter.

August 1952 Journal of the SMPTE Vol. 59

ment may be only slightly affected, the
phototube of the usual sound reproducer
will see a reduced image contrast with
definite effect on the reproduction of
sound.

Measurements of silver sulfide sound
tracks by densitometers with phototubes
having S-4 response or by visual instru-
ments are to be discouraged.

Standardized Densitometry

The interchange of useful information
on sound track printing conditions would
be greatly facilitated by standardized
densitometry. The method most likely
to produce an acceptable degree of
correlation requires the use of an inter-
ference filter2*3 to restrict the response of
the densitometer to a bandwidth of a few
millimicrons. The density character-
istics of one type of interference filter
are shown in Fig. 4. With such a
filter, the effects of variations of the
wavelength of peak sensitivity, shift of
peak due to color temperature of the
light source, the effects of aging, and
differences in spectral sensitivity of
phototubes are virtually eliminated.
In fact, practically the only sources
of error that remain are due either to
the geometry of the instrument or to
error in the determination of the wave-
length of peak transmission of the filter.

The effects of tube responses are
eliminated so that the same density is
indicated whether an S-l or S-4 response
is used. Of course, the sensitivity with
an S-4 response is so much less that it
would seldom, if ever, be used.

The filters are relatively dense so
that as much as two density ranges
may be lost. This restricts the choice of
wavelengths for standardized densitom-
etry. If 550 m/i were chosen, the
required unfiltered range for the densitom-
etry of a sound track on Kodachrome
film would be 0 to 6, since it would be
necessary to be able to read to a density
of about 3.2. However, at 800 mp.
the unfiltered density range required
would be only a little more than 3,

since the maximum density at 800 mju
of the reversal silver sulfide sound
track on Kodachrome film is now under
1.0.

Acknowledgment

The author wishes to acknowledge
the contribution of Jack Pinney and
Edward Letzer of the Color Control
Division in obtaining materials and data
for study of the problems of densitom-
etry of silver and silver sulfide deposits.

References

1. Zworykin and Ramberg, Photoelectricity
and Its Applications, John Wiley, New
York, 1949, p. 15.

2. Bruce H. Billings, "Narrow band
optical interference filters," Phot. Eng.,
2: 45-52, 1951.

3. Harry D. Polster, "A symmetrical all-
dielectric interference filter," /. Opt.
Soc. Am., 42: 21-23, Jan. 1952.

Discussion

John G. Frayne (Westrex Corp.} : I'd like to
ask if those figures given for density are
diffuse density?

Mr. Lovick: They're diffuse. These
densities are measured on the Western
Electric RA - 1100B Densitometer modified
for this purpose.

Dr. Frayne: With the interference filter
in the optical system, what density are you
able to measure with the existing ampli-
fier?

Mr. Lovick: We have modified the am-
plifier so that even with the additional
filter we still get a density range of 4.

Dr. Frayne: Is that information going
to be available? We'd like to know about
it.

Mr. Lovick: You mean how to modify
the amplifier?

Dr. Frayne: Yes.

Mr. Lovick: It's only necessary to change
a few resistors in the preamplifier.

Dr. Frayne: Even that's worth knowing.
Are the interference filters available?

Mr. Lovick: Yes. We've obtained some
from Bausch & Lomb. The tolerance
which I think we should require is about
plus or minus 2 millimicrons in order to
get good correlation.

Robert C. Lovick: Densitometry of Sulfide Tracks

Modulated Air Blast

for Reducing Film Buckle

By WILLY BORBERG

Present-day demands for high-intensity light sources point up the need for a
suitable technique for reduction of excessive film buckle. Air jets which
direct a continuous air flow against one or both of the film faces have been
proposed. This technique does not, however, take into account the cyclical
nature of film surface deformations during projection. It is found that improved
performance can be obtained with a modulated air blast which is synchronized
to the frame cycle. This paper describes the cyclical effects involved and
shows why the modulated air blast is to be preferred over continuous air blast.
It presents experimental data regarding buckle magnitudes in 35mm film and
describes the experimental equipment.

_L HE TYPE OF BUCKLE with which WC

are concerned in the present discussion
is a deformation which takes place during
the frame cycle while the film is in the
aperture. It may leave no record of its
existence on the film after projection.
It can be made visible by stroboscopic or
high-speed photographic techniques, ap-
pearing as a rythmic — almost breathing
— motion of the film surface in the aper-
ture. It produces deterioration of image
focus during part of the rapidly recurring
projection cycle.

The causes of film buckle have been
investigated and described before. Car-
ver, Talbot and Loomis,1-2 as well as
Kolb,3 have done considerable work on

Presented on April 25, 1952, at the Society's
Convention at Chicago, 111., by Willy
Borberg, General Precision Laboratory,
Inc., Pleasantville, N.Y.

the subject in connection with broad
studies of film performance. They have
developed the terminology needed for
presentation and their usage will be
followed. The present discussion will be
concerned with those effects which vary
during the film frame cycle. However,
a brief statement of the basic factors will
not be amiss.

Each single picture frame goes through
a cycle which starts with pulldown into
the aperture, proceeds through the first
exposure, the flicker blade cutoff and the
second exposure, and ends with the pull-
down of the next frame. During the two
exposure intervals the film arrests some
of the radiant energy from the light
source and transforms it into heat. This
causes the film to buckle (or bulge) in a
manner very similar to that observed in
the operation of a bimetallic element.

August 1952 Journal of the SMPTE Vol.59

The emulsion, being more opaque than
the base, absorbs energy, expands and
becomes the outer or convex surface of
the bulge. The magnitude of the de-
formation produced varies continuously
during the frame cycle and by an amount
which is more than sufficient to affect
sharpness of image focus.

The emulsion side of 35mm film is
toward the light source; and hence the
film tends to move toward the light, away
from the lens, while it is in the aperture.

In accordance with the accepted ter-
minology, the deformation is called
negative when the emulsion side is convex,
and conversely, positive when the emul-
sion side is concave. Flat film is con-
sidered to have zero deformation.

The film upon entering the projector
gate is not necessarily flat, but may have
a slightly positive curl, the magnitude of
which depends to some extent on the age
and condition of the film. It appears
that there is some shrinkage of both emul-
sion and base, the emulsion shrinking
more than the base, so that the resulting
curl is slightly positive. Typical posi-
tive displacement at the center of cold
35mm film as it enters the gate is between
zero and 0.010 in.

Instantly upon registration of the film
frame with the aperture, the shutter
uncovers the light for the first exposure
of the cycle. Light energy is absorbed
in the emulsion and transformed into
heat. The expanding emulsion causes
the exposed portion of the film frame to
move from its initial zero or positive
position, shifting it to a negative position,
and causing it to take a somewhat spheri-
cal shape. There is a constantly increas-
ing deformation during the first exposure,
and a constantly changing distance of the
emulsion surface with respect to the lens.
Upon interception of the light by the
flicker blade, further movement of the
film surface toward the light source
comes to a halt. With no light on the
film, heat absorption by the film cannot
take place. Instead, there is a loss of
heat which causes the film to recede

slightly toward the zero plane. At the
start of the second exposure, the film
surface stands somewhere between zero
and its former maximum negative posi-
tion. During the second exposure, the
film continues its excursion negatively,
first rapidly, then leveling off. At the
end of this exposure the film reaches a
more negative position than at the end
of the first exposure.

Figure 1 shows the correlation between
the movement at the center of the film
surface and particular instants in the
frame cycle. The same movement oc-
curs at points off the center of the film
surface, though to a smaller degree. A
significant effect which may be noted is
that the center of the film, which is in
motion during the entire cycle, travels
through and beyond the acceptable focus
limits defined by the depth of the focus
of the projection lens.

The projectionist, whose eye just can-
not follow this rapid sequence of events
(48 times per second), has to pick a
"best average focus" position of the pro-
jection lens, somewhere between the
maximum positive and maximum nega-
tive of the two exposure periods. If he
judges the focus at the center of the
screen, he picks a "best average focus"
position near the maximum negative
buckle of the first exposure. The re-
maining, earlier part of this exposure pro-
duces only a poor and undefined image
on the screen. A portion of the second
exposure, also, is beyond the limit of good
image definition on the screen, and good
optical performance can take place only
during that part of the exposure in which
the film displacement line lies within the
depth-of-focus range. The "best average
focus" thus obtained gives the best at-
tainable image at the center of the screen.
Actually, in practice, the projectionist
may choose a slightly less negative lens
position, which is a compromise to gain
relatively fair overall definition across
the whole screen. Even this compromise
results in a fairly large percentage of
"out-of-focus" time during a cycle.

Willy Borberg: Reducing Film Buckle

DEPTH OF

FOCUS
"RANGE
OF LENS

Fig. 1. Film displacement due to buckling at center of frame — No Air.

Fig. 2. Test equipment used to determine film buckle magnitudes and time relations,
96 August 1952 Journal of the SMPTE Vol. 59

For the conditions demonstrated in Fig.
1, good optical performance is attained
during only about 40% of the first ex-
posure and 60% of the second exposure,
or a total of only 50% during a complete
frame cycle. This is the best the pro-
jectionist can do.

The figures so far presented demon-
strate the magnitude of the defect with
which we are concerned, since they have
been obtained with representative equip-
ment, operating under conditions which
might be found in any large theater.
For test purposes, the projector was fitted
with facilities to determine the various
focus positions of the 5-in. focal length
f/\ .9 projection lens.

The light source was a Hi-Candescent
Arc Lamp, with F-2 condensers, burning
at 160 amp and delivering about 9000
1m to the screen with the shutter running.

All focus settings were made with the
aid of Simplex Screen Scopes. The 8-
power magnification thus provided en-
abled lens adjustment with greater pre-
cision than could have been attained by
direct observation of the screen from the
projector.

The film plane position along the op-
tical axis was measured directly in terms
of lens displacement, a dial indicator cali-
brated in thousandths of an inch being
affixed to the lens mount for this purpose.
Initial calibration for zero position on
the dial indicator was made by focusing
the lens to produce a critically sharp
image of a conical hole in a flat steel
plate, the small end of the hole being in
the same plane as the emulsion contacting
surfaces of the film trap. Up to this
point, the method and equipment are
essentially the same as those employed
and described by Kolb.3

The addition of a viewing shutter to
the equipment enabled observation of
successive phases of the cyclicly varying
film frame motion (see Fig. 2). The
viewing shutter's drive-motor stator was
rotatable so that the shutter opening of
about 9° could be phased with relation
to the synchronously running projector.

This stroboscopic arrangement made it
possible to view the screen image in
small time increments of about 1 msec
through all exposure phases of successive
frame cycles. The film emulsion position
during any specific phase of the exposure
periods could thus be established with-
out regard to possible out-of-focus condi-
tions during the remaining unobserved
portions of the cycle. Dial indicator
readings were then recorded in relation
to the phase settings. A contactor on the
projector shutter timed a short-duration
light flash for establishing correct phase
reference.

The equipment as described permitted
studies of film behavior under actual
operating conditions.

The technique of air-blast cooling of
film, by which opposing air forces of the
front and rear jets are adjusted so as to
produce a force for positioning the film,
was found to be at best a partial solution
to the problem. It is possible to move
the film by this method and to shift the
average focus position; the resultant
force, however, acts upon the film con-
tinuously, and therefore, cannot correct
for the intermittent cyclical frame de-
formations caused by the internal buck-
ling forces in the film which occur during
the two exposure periods.

The center of each frame travels over
a range of about 0.020 or 0.030 in. This
range is not greatly reduced by applica-
tion of a continuous displacing air force
(Fig. 3). The continuous jets produce a
shift in average focus position; this, by
itself, only slightly alters the ratio of
"in focus" and "out-of-focus" intervals.
The air serves primarily as a cooling
agent, preventing possible damage to the
film in the form of embossing or blister-
ing or the formation of permanent buckle.

It was felt that, because of the cyclical
nature of the film frame deformations
involved, any corrective action to neu-
tralize the defects should be similarly
cyclical. Hence, the following approach
(Figure 4) was tried:

Willy Borberg: Reducing Film Buckle

CONTINUOUS AIR FROM FRONT JE1

DEPTH OF
FOCUS
RANGE
OF LENS

I 1

f I f 1 I

CONTINUOUS AIR FROM REAR JET
Fig. 3. Film displacement due to buckling at center of frame — Continuous Air.

(a) The air from the front jet was
modulated by means of a rotary valve
driven from the shutter shaft.

(b) The air from the rear jet was not
modulated and the steady stream of air
from this jet was used to force the film
toward the lens, thus partly neutralizing
the internal forces, which tend to make
the film take a deep negative buckle
under the influence of light.

(c) The correcting air pulses from the
joint jet were timed so that the resultant
forces from both front and rear jets op-
posed the cyclicly varying buckle forces.
The motion of each film frame on the op-
tical axis could thus be controlled.

Figure 5 illustrates the timing of the
jets and shows that the position of the
film frame can be held steady within
fairly close limits. It should be noted
that the excursions of the film frame sur-
face can be confined to the depth-of-
focus range of the lens. Good optical

performance is thus attained over vir-
tually the entire frame cycle.

Figure 5 also shows that a negative
displacement of approximately 0.012 in.
is allowed to exist at the center of the
frame. The question may be asked,
"Why is the process not carried beyond
this point so as to bring the displacement
to zero?" There are two reasons for not
doing so. The first, as pointed out by
Kolb, is concerned with the performance
of the projection lens. In most projec-
tion lenses the focal plane of field is not
truly a plane, but rather a curved surface.
For best performance in this respect, the
film is allowed to approximate this sur-
face. The second reason is that flat film
seems to be somewhat flaccid under the
influence of air flow, as compared to film
which is bowed to even a slight degree.

Since the film can be kept within the
depth-of-focus limit of the projection lens
during nearly the entire time of the two

August 1952 Journal of the SMPTE Vol. 59

ROTORY VALVE
DRIVEN FROM
SHUTTER SHAFT

FEED SPROCKET

FILM DISPLACEMENT
INDICATOR

INTERMITTENT— ^/^"^N
SPROCKET J Q

>^>

FOCUS KNOB

(

Fig. 4. Arrangement of air jets and film displacement indicator.

DEPTH OF
_ FOCUS
RANGE
OF LENS

CONTINUOUS AIR FROM REAR JET
Fig. 5. Film displacement due to buckling at center of frame — Pulsed Air.

Willy Borberg: Reducing Film Buckle

exposure periods, there is marked im-
provement in screen image definition.

Experiments so far have been directed
toward the use of the modulated front
jet. It is quite possible to use the oppo-
site arrangement of a steady front jet
and pulsed rear jet. For better cooling,
however, it seems advisable to let the
continuous air stream wash the emulsion
side of the film, relying on the front jet
as the position correcting agent. A
pulsed combination of both jets may
offer some advantages in air economy, but
has not been tried.

References

1. E. K. Carver, R. H. Talbot and H. A.
Loomis, "Effects of high-intensity arcs
upon 35mm film projection," Jour.
SMPE, 41: 69-87, July 1943.

2. E. K. Carver, R. H. Talbot and H. A.
Loomis, "Film distortions and their
effect upon projection quality," Jour.
SMPE, 47: 88-93, July 1943.

3. F. J. Kolb, Jr., "Air cooling of motion
picture film for high screen illumination,"
Jour. SMPE, 53: 635-664, Dec. 1949.

Discussion

R. T. Van Niman (RCA Victor Div.) : I
perhaps missed something in the early part

of the talk, but did you consider whether or
not the amount of deformation varies with
the type of picture material? I believe
Mr. Kolb pointed out that the amount of
buckling depends to some extent upon the
density of the film in the aperture at that
time.

Mr. Borberg: Yes, it does matter, but
there is always deformation, even with a
very low density. The worst condition
occurs with a dark film, and necessarily the
amount of buckle depends also on the
energy of the light source.

Mr. Van Niman: No attempt has been
made to compensate for the variation in
density along the film then?

Mr. Borberg: No. A photocell device
operating from screen illumination to con-
trol air blast has been considered. Such a
device would compensate for scene-to-scene
variations which are beyond the projec-
tionists' ability to follow, but the instru-
mentation just hasn't gone that far.

W. W. Lazier (National Carbon Co.}:
Does the intermittent air blast make much
audible noise?

Mr. Borberg: Yes, there is some noise,
but it's not very disturbing and it does not
exceed the noise of jets with continuous air.
There is a purring noise, I might say.

100

August 1952 Journal of the SMPTE Vol. 59

A Method of Direct- Positive Variable-Density
Recording With the Light Valve

By O. L. DUPY

In this system the light valve is placed in the cathode circuit of a nonlinear
amplifier, the nonlinearity being of such a nature that the relation between
the input to the amplifier and the transmission of the developed film is linear
over a large percentage of the film-transmission range. The method of de-
termining the shape of the necessary nonlinearity and how it is produced is
described.

.AGNETIC FILM has proved to be an
excellent medium for sound recording in
the motion picture industry. However,
considering the well-established editing
techniques and the existing editing and
viewing equipment, it will be some time
before the magnetic record will replace
the photographic sound record for use
throughout the studio. The economical
method of obtaining this record is to
transfer the sound electrically from the
magnetic record to a film that has the
characteristics of a print when developed.
The making of direct-positive prints
by electrical printing has several ad-
vantages. The most important is the
saving of the negative film and the cost
of the development and printing of this
film. Also, the reduction of the time
that elapses between the recording and

Presented on April 25, 1952, at the Society's
Convention at Chicago, 111., by John G.
Frayne for the author, O. L. Dupy, Metro-
Goldwyn-Mayer Sound Dept., Culver City,
Calif.

the delivery of a print is sometimes of
great importance. Another advantage
is the reduction of the film background
noise by the elimination of the film noise,
inherent in the negative, which is added
to the print. Another advantage is the
elimination of the flutter introduced by
the printer, which is generally the con-
tributor of a good percentage of the total
flutter in film recording.

The main disadvantage in obtaining a
linear recording from a variable-density
type of photographic characteristic is the
rather elaborate amplifier system re-
quired to offset this distortion, but one or
possibly two such units will handle all
the daily printing for a large studio.
The push-pull variable-area method of
recording has been successfully adapted
to produce these direct-positive prints.*
With the push-pull system a higher track

*L. I. Carey and Frank Moran, "Push-pull
direct-positive recording — an auxiliary to
magnetic recording," Jour. SMPTE, 58:
67-70, Jan. 1952.

August 1952 Journal of the SMPTE Vol. 59

101

150
n

I- 40

50 100 150

EXPOSURE C CATHODE CURRENT )

Fig. 1. Film-recording characteristic.

200

RESULT

102

Fig. 2. Correcting nonlinear amplifier characteristic.
August 1952 Journal of the SMPTE Vol. 59

density than normal can be employed
because of the cancellation of the cross-
modulation products in push-pull re-
production, thus producing results that
equal the cancellation achieved by the
normal negative and print process. The
nonlinear exposure versus light-trans-
mission characteristics of the film enters
into the problem of making a variable-
density direct-positive. In order to de-
termine the nonlinear characteristics,
samples were exposed by sending direct
current in fixed steps through the light
valve in a standard recording machine.
These strips were processed using the
M-G-M standard release development
procedure. The resulting strips were
measured by inserting a 400-cycle chop-
per in the light beam of a standard film-
reproducing machine and measuring the
audio signal at the output of the photo-
electric cell amplifier. By this pro-
cedure, the test included all the variables
encountered in the recording and re-
producing systems.

The resulting characteristic is shown
in Fig. 1 . The above tests were repeated
over a period of time in order to check
the stability of the variables involved.
The results proved that this method of
making a variable-density direct-positive
was practical.

Figure 2 shows the schematic of an
amplifier, the characteristics of which are
the reciprocal of Fig. 1 . The first stage
of the amplifier has a practically linear
characteristic and is used as a voltage
amplifier directly coupled to the second
and third stages or sections. The noise-
reduction control voltage is fed to the in-
put grid in series with the secondary
winding of the input transformer. The
second stage controls the shaping of the
middle and upper end of the curve by
being biased negative almost to cutoff;
the signal received from the cathode re-
sistance of the first stage is such that it is
linear for the lower half of the range, and
becomes nonlinear as the driving signal
increases. The third stage controls the
shaping of the extreme upper end of the

curve. This is accomplished by biasing
the grids negative beyond cutoff and
driving them with a signal voltage that
will cause the tubes to conduct only on
the positive peaks of the signal.

Figure 3 shows the method of obtain-
ing this curvature by using a number of
tubes in parallel, the grids of which are
biased to operate at various points in the
nonlinear portion of their grid volts
versus plate-current curves. The over-
all shape is obtained by adjusting the
balance between the grid and signal
voltage, and the number of tubes used.

The light valve must be directly
coupled to this amplifier because the re-
sulting distorted signal is composed of
direct current; the signal fundamental
and a large amount of harmonics of the
signal, and in addition the noise-reduc-
tion signal must be altered by this circuit.

Figure 3 shows the contributions of all
three stages and the overall character-
istic of the nonlinear amplifier. A
Western Electric RA-1238, 200-mil push-
pull variable-density light valve was used
in these studies and in recording the
demonstration film which was run at the
close of the paper. It is necessary to
employ one amplifier of the type shown
in Fig. 2 for each component of the push-
pull valve. This results in a classical
type of push-pull reproduction, and a
higher degree of an overall linearity is
obtained than when using a standard
single track. However, good quality is
obtained from a single track provided
care is taken in the setting of the operat-
ing parameters.

A direct current is applied to the light
valve, in opposition to the cathode cur-
rent, for adjusting the static opening of
the valve for zero signal input. A noise-
reduction bias current is applied to each
component of the light valve through its
associated amplifier. Since the resulting
sound track is in effect a positive, the
ribbons are either mechanically or elec-
trically biased open, rather than closed
as in a normal negative-positive record-
ing. The action of the input noise-

O. L. Dupy: Direct-Positive Variable-Density Recording

103

104

August 1952 Journal of the SMPTE Vol. 59

£ 30

300 200 100 0 100 200 300 '400 500
VALVE CURRENT

Fig. 4. Predistortion curve for extended range recording.

reduction voltage then serves to cancel
this d-c bias, the minimum spacing of
the ribbon being obtained for maximum
signal input. Experience has shown
that noise reduction equivalent to that
obtained in ordinary recording can be
obtained in this method of recording.

The shape of the correcting curve was
checked by recording signals at various
levels and measuring the distortion.
The part of the curve that was incorrect
was found by measuring the distortion of
a low-level signal that was moved in
steps, over the complete range of the
characteristic, by independently varying
the noise-reduction control voltage.
This information was used for final in-

dividual adjustment of each section of
the amplifier.

It should be noted that the current
required from the B supply varies at both
the signal envelope and audiofrequency
rates. A regulated B voltage supply
having a rapid recovery rate and a low
internal impedance of about 0.9 ohms was
satisfactory. The necessary mainte-
nance, checking and adjustments have
been reduced to a routine. We antici-
pate that experience will produce a sys-
tem with better uniformity and quality
than the negative and positive system.

Having developed a nonlinear system
with adjustable characteristics, we have
adapted it to extend the volume range
of the print made from a standard nega-

O. L. Dupy: Direct-Positive Variable-Density Recording

105

tive variable-density recording. This
is done by making the amplifier linear
over the corresponding linear film-
transmission range and then nonlinear
in the direction necessary to correct the
film curvature in the high transmission
range. The maximum volume output
has been increased by approximately 6
db. Figure 4 shows a typical overall
negative-positive exposure versus trans-
mission curve, and illustrates the distor-
tion that occurs when attempting to use
the full transmission range of the film.

Figure 4 also shows how by distorting the
input signal a sine-wave result can be
produced that extends over the trans-
mission range from 5 to 80%.

M-G-M has used the direct-positive
system described in this paper for several
months experimentally to make tempo-
rary recordings for previews and in other
intrastudio operations. The sound qual-
ity has proved to be invariably satis-
factory indicating that this method of
transferring from magnetic originals to
direct-positive density is quite feasible.

106

August 1952 Journal of the SMPTE Vol. 59

International Auxiliary Language
for Motion Pictures

Before reading the article by Otto C.
Bixler beginning on page 109, please
read the page of Interlingua translation
immediately following this and see how
much of it you can understand at sight.

Interlingua is the nearest attainment
of a workable international language for
the contemporary world which modern
linguistic science can produce. This is
the claim of the International Auxiliary
Language Association (I ALA) as the
result of many years of research on one
of the most timely problems of communi-
cation. lALA's research was set up by-
noted linguists in Europe and the United
States and has been carried out by a
staff of experts in different languages.

lALA's staff has devised a system for
screening off words which are inter-
nationally known and for giving them
standardized forms and definitions. Some
27,000 of them are presented in the
Interlingua-English Dictionary. A simple
grammar employing only those features
which languages have in common has
been prepared to operate this natural
international vocabulary.

Interlingua includes general and tech-

This presentation has been prepared
through the kindly offices of Dr. Alfred N.
Goldsmith. This brief description of In-
terlingua has been prepared by Mary
Bray, and Dr. Alexander Code has trans-
lated into Interlingua the page immediately
following. Both are staff members of the
International Auxiliary Language As-
sociation.

nical words of every type. Words from
the Romance languages dominate the
general vocabulary. The technical
terms drawn directly from Latin and
Greek are in the majority for the reason
that the international world of science
and technology is constantly creating its
own international language.

While Interlingua is basically a West-
ern language it does not exclude any
Oriental words in international circula-
tion.

An auxiliary language to supplement
mother tongues should represent as
many national languages as possible.
Interlingua has the psychological asset of
looking familiar to a world of readers
comprising North America, South
America, Europe, and readers in Asia
and Africa who know one of the Euro-
pean languages.

IALA is bringing Interlingua to the
attention of groups of scientists and tech-
nologists. The Association will welcome
suggestions and comments from readers
of the Journal of the SMPTE as to possible
collaboration with engineering groups
at the heart of the motion picture indus-
try. The eventual use of Interlingua in
export-film captions is not beyond prac-
tical imagination in the development of
world markets.

Alfred N. Goldsmith, Past-President
of the SMPTE, has been a member of the
Board of Directors of IALA since its
founding. The headquarters of IALA
are at 420 Lexington Ave., New York 17,
N.Y.

August 1952 Journal of the SMPTE Vol. 59

107

Un commercial phonoregistrator binaural

Per OTTO C. BIXLER

Le disveloppamento hodierne del apparatura de phonoreproduction es multo
avantiate. Proque le avantages del registration stereophonic ha previe-
mente essite demonstrate, nos ha credite que le proxime desiderato re appara-
tura s commercial esserea le fabrication a precio rationabile de un sy sterna
binaural. Nos presenta hie un revista del factores theoric implicite in binaural
phonoregistration e reproduction, insimul con un description del apparatura
technic disveloppate pro satisfacer le requirimento de alte qualitate acustic
intra le limites de rationabile costos total. Nos describe alicun nove problemas
e effectos incontrate in iste programma de disveloppamento.

Desiderates structural del apparatura
binaural

Le decision a preparar pro uso com-
mercial un binaural registrator a banda
resultava del desiro de suppler phono-
registrantes con ameliorate e nove
methodos de presentation. Esseva pren-
dite in consideration le facto que usque
nunc nulle binaural apparatura ver-
mente commercial ha essite presentate al
publico ben que numerose firmas (inter
illos Bell Laboratories, Fox Studios,
Warner Bros., e alteres) ha facite multo
satisfactori demonstrationes stereophonic.
Post le qualitate de phonoreproduction
habeva essite avantiate a su presente alte
fidelitate con excellente responsas a
frequentia, minimal cambiamentos de
phase e bon reproduction transiente, on
recognosceva que alique, nonobstante,
mancava. Iste "alique" es le distribu-
tion spatial del sono original. Le repro-
duction monaural del sono emanante de

Presentate le 24 de april, 1952, al conven-
tion del Societate a Chicago, 111., per Otto
C. Bixler del firma Magnecord, Inc., 225
W. Ohio St., Chicago 10, 111.

multiple fontes a disposition spatial in-
troduce distortiones spatial. Le optime
methodo a eliminar tal distortion es re-
producer sonos stereophonicamente. Ver
stereoreproduction de sonos es technica-
mente satis difficile e relativemente cos-
tose. Le secunde optime methodo es le
binaural phonoregistration e reproduc-
tion. De facto, sonos binaural repro-
ducite per medio de receptores auricular
resulta pro le auditor in un quasi per-
fecte recreation del phonoimpacto origi-
nal.

Theoria de audition binaural

In principio, le factores theoric del
phonopresentation binaural visa a pro-
ducer, a un plus tarde tempore, le mesme
amplitude de sono e relation de phases in
cata un del duo aures del auditor como si
ille habeva essite originalmente presente.
On debe notar que le aures e le cerebro
del auditor constitue un systema de com-
putation directional basate super lor
sensitivitate a phases e amplitudes. Iste
systema dual involve un area intersec-
tional de "sensitivitate contra frequen-
tia" que es determinate sequentemente:

108

August 1952 Journal of the SMPTE Vol. 59

A Commercial Binaural Recorder

By OTTO C. BIXLER

Present-day sound recording-reproducing equipment is at a very high state
of development and, since the benefits of stereophonic recording have been
previously demonstrated, it was believed that the next desirable step in
commercial equipment would be the manufacture of a reasonably priced
binaural system. A review of the theoretical factors involved in binaural
sound recording and reproduction is presented along with a description of
the technical equipment developed to fill the needs of high-quality binaural
sound consistent with a reasonable overall equipment cost. Some novel
problems and effects experienced in this development program are described.

Binaural Equipment Design Objective

The decision to design a commercial
binaural tape recorder was based upon
the desire to provide the recording field
with an enhanced, novel method of
sound presentation. Consideration was
given to the fact that to date no true
commercial binaural equipment had
been presented to the public although
many concerns, including Bell Labora-
tories, Fox Studios, Warner Bros., and
others, have given highly satisfactory
public demonstrations of stereophonic
sound. After the quality of sound
reproduction was brought to its present
high fidelity with excellent frequency
response, minimum phase shift and good
transient reproduction, it was realized
that something was still lacking. That
something is the normal spatial dis-
tribution of original sound. Monaural
reproduction of a spatially disposed

Presented on April 24, 1952, at the Society's
Convention at Chicago, 111., by Otto C.
Bixler, Magnecord, Inc., 225 West Ohio
St., Chicago 10, 111.

multiple sound source introduces spatial
distortion. The best way to eliminate
this distortion is to reproduce sound in a
stereophonic manner. True stereo-
sound is quite difficult of technical
achievement and is comparatively costly.
The next best method is the use of
binaurally recorded and reproduced
sound. As a matter of fact, when bin-
aural sound is reproduced through
earphones an almost perfect re-creation
of the original sound impact upon a
listener is obtained.

Binaural Hearing Theory

Basically, the theoretical factors in-
volved in binaural sound presentation
are aimed at producing, at a later time,
the same sound amplitude and phase
relationship in each of a listener's two
ears as if he had been present originally.
It is to be noted that a listener's ears
and brain constitute a directional com-
puting system based upon their phase
and amplitude sensitivity. This dual
system has a sensitivity-versus-frequency
crossover area determined as follows:

August 1952 Journal of the SMPTE Vol. 59

109

Fig. 1. High frequencies pass by an observer's far ear. Low frequencies readily
curve around the cranial obstruction to the far ear.

The average human-ear phase-sensi-
tivity range is from some very low fre-
quency up to approximately 800 to
1000 cycles/sec, which thus allows a
perception of directivity by binaural
phase comparison over this range. The
amplitude sensitivity range of the indi-
vidual ear is from the lowest frequency
perception point up to the highest fre-
quency perception limit within the
dynamic volume range of the ear. This
dynamic volume range is defined by the
standard Fletcher-Munson hearing
curves modified by the room masking
noise level.1

By simple amplitude comparison a
mental computation of directivity may
be obtained, except as limited by the
physics of sound propagation. This
means that due to the lack of directivity
of low-frequency sounds below, say, 800
to 1000 cycles, the ear's amplitude-
detection ability is of no avail, since a

low-frequency sound wave curves around
the head without appreciable amplitude
loss. Therefore, the amplitude-derived
directional sensitivity of the binaural
ear arrangement falls off rapidly. This
is exemplified by the fact that a 1000-
cycle/sec tone directed toward a listener
from one side of his head produces only
a 3-db level difference at his far ear
compared with the near ear; a 10,000-
cycle/sec tone under the same condi-
tions produces a 30-db level difference
(Fig. 1).

It may be shown that the portion of
normal auditory perspective due to
phase sensitivity is related to the lineal
distance between the human ears. Let
us assume that a theoretical observer
has a between-the-ears distance of, say,
6.78 in. Under certain environmental
conditions the speed of sound in air is,
say, 1130 ft/sec. The maximum fre-
quency, /, that the ears may compare

110

August 1952 Journal of the SMPTE Vol. 59

phase on, has a half wavelength, X/2,
equal to the distance between the ears
(Fig. 1). Therefore, if:

11 SO
X = 6.78 X 2/12; then/ = — - =

1130

7S212

That is, the maximum possible frequency
for binaural phase detection by this
theoretical observer is in the order of
1000 cycles/sec or less.

Most speech sound sources possess
frequencies both above and below the
crossover frequency range of from 800
to 1000 cycles. Not only does this
enable the observer to compare angular
location by both phase and amplitude
methods (and to derive a more accurate
location), but since phase shift of a given
frequency is a function of both angular
position as well as distance, it provides
a measure of the distance to the sound
source.

In addition to the localization system
defined by the base distance between
the ears and the mental computation
of angles, the mind has an additional
distance-computing ability based upon
the ratio of direct sound to reverberant
sound impinging upon the eardrum.

Microphone Placement

In view of the above, it becomes
immediately apparent that in order to
record binaurally for later binaural
reproduction some care should be
exercised in microphone placement.

The first basic principle underlying
microphone placement is that the
perpendicular bisector of the line joining
the pickup microphones represents the
center line of a fictional listener's posi-
tion. During reproduction, the loud-
speaker placement should be such that
the perpendicular bisector of the line
joining the loudspeakers coincides with
the real listener's center line. This
arrangement results in both depth and
lateral stereophonic "image" location,
dependent upon both phase and the

intensity ratio of the direct sound picked
up by the two microphones.

The second principle underlying
microphone placement affects the ap-
parent position of the sound behind the
immediate foreground. The distance
of the source from a single microphone
is also determined mentally by a com-
parison of the reverberant sound to the
direct sound. The most accurate mental
calculation is made when this ratio is
not in the extremes. Therefore, both
exceedingly close and overly distant
microphone placements are to be
avoided.

Under a strict binaural microphone
arrangement the two microphones should
be relatively close together and have
individual pickup patterns approxi-
mating those of the human ear; the
placing of an acoustic septum between
the microphones would be desirable.
Under an expanded arrangement, where-
in a simple stereophonic system is ob-
tained, the microphones are spaced
quite widely apart and a third micro-
phone with isolation amplifiers and
attenuators is added midway between
these two primary microphones. The
object of the center microphone is to
feed a small amount of sound energy
to both recording channels and thereby
to correct for the spatial distortion
occasioned by moving the primary
microphones apart.4 Unless this cor-
rection is made, some depth location
error occurs, especially in the area
midway between the primary micro-
phones. If some depth location error
may be permitted, which it may be if
the sound is not associated with a con-
current motion picture, then it is readily
possible to omit the center microphone.

Binaural Presence — Listening

The physiological sense satisfaction
that yields the psychological impression
of being present in a nonexistent room is
the startling factor in listening to a
binaural recording for the first time.
The sense of "presence" obtained is

Otto C. Bixler: Binaural Recorder

111

considerably different from the normal
usage of this word. In accepted sound
practice the reproduction objective is
to bring the sound source into the
presence of the listener. Listening to a
binaural recording can best be de-
scribed as literally taking the listener
into the presence of the scene where
the original recording was made.

This effect of realism is particularly
effective when listening with headphones.
When considering theoretical factors it
would not seem that loudspeaker listen-
ing would be very effective for binuaral
reproduction. However, listening tests
readily convince one that considerable
enhancement is still retained with
speakers although not of such a high
order as that of earphone listening. The
use of earphones prevents a listener
from turning his head to aid in localizing
sound sources; loudspeaker reproduction
on the other hand allows a listener to
retain this mechanical aid to localiza-
tion. Loudspeaker placement is of con-
siderable importance in good reproduc-
tion. The use of too large or too "live"
a room or too great a listener distance
greatly reduces the effectiveness of
binaural loudspeaker reproduction.

Random Noise Correlation

An unexpected effect was noted when
some rather poor recordings were un-
intentionally made and then played
back. When the recording medium or
equipment random-noise level is high
with respect to the level of the recorded
signal a unique result ensues. The
random nature of this white noise is
such that it allows false phase and
amplitude coincidence to be correlated
by the brain to produce apparently
localized sources of noise. The localiza-
tion means focused listening attention;
the effect thus results in raising of ap-
parent loudness of discreet noise "pulses."
Since these pulses are strictly random
mental correlations, their number is
far less than the actual number of white
noise "pulses"; therefore, the net effect

is a coarsening and apparent increase
of the background noise level to the
listener. Practically speaking, this
means that binaural recordings made
for maximum music appreciation should
be made with particular care toward
maintaining the best overall measured
signal-to-noise ratio.

The Tape Transport

The development of the binaural
tape transport from a standard recorder
was very desirable in order to keep
manufacturing costs down and allow
sales at a reasonable price to the cus-
tomer without the necessity for designing
a new special unit with its attendant
reflected high sales price. It was found
possible to extend the development of a
standard Magnecord PT63-A tape trans-
port mechanism for use in a binaural
recording system. This basic tape trans-
port mechanism possesses an assembly
incorporating three heads. The tape
passes in succession over, first, the erase
head, then, the normal recording head,
and, thence, over the tape monitor head
before it is pulled by the capstan and
fed to the take-up reel.

Consideration was given to the possi-
bility of retaining the tape monitor
feature for the binaural system. How-
ever, it was determined that the addi-
tional system complexity would add
materially to equipment size and costs
because of the immediate requirement
for two monitor heads and two amplifier
monitoring channels as well as extra
controls. The mechanical layout of
the front panel of the existing PT63-A
tape transport unit would also be
unduly complicated by the addition of
the two extra magnetic heads required.
It was, therefore, decided that the
normal full-track record head would be
replaced by a half-track record head
and the position normally occupied by
the monitor head would be used for a
second half-track record head for the
other half of the tape.

112

August 1952 Journal of the SMPTE Vol. 59

It is of interest to note that in this
standard unit the erase head forms the
principal load for the 60-kc erase and
bias oscillator with the record head bias
coil being a relatively small series
impedance in the circuit. It was
therefore possible to add the bias
winding for the second recording head
in series with the existing erase and
record heads without any appreciable
net change in bias or erase currents.
Using the above-described arrangement
it was then only necessary to supply
proper pole pieces, and to reconnect the
internal wiring to the heads to accom-
modate the second recording channel.
Plug and receptacle arrangements are
so chosen as to automatically maintain
channel identity in the interunit cables.

With the exception of the nameplate,
there is no apparent difference between
a binaural Magnecorder and a normal
single-track unit unless the magnetic
head covers are lifted to allow a view
of the half-track pole pieces which do
the recording. The half-track pole
piece consists simply of a normal full-
track pole piece with approximately
^ of the Mu-metal cut away and a brass
insert soldered into its place in order to
fully support the tape.

The Amplifier Unit

The development of a binaural re-
cording and reproducing amplifier was
essentially a specialized packaging job
which involved building a new portable
dual amplifier unit, each amplifier
having all the characteristics of existing
unit standard amplifiers. The packag-
ing was accomplished with only a minor
increase in space and weight for the dual
amplifiers over that required by a similar
existing single-channel amplifier. The
latest techniques in the use of miniature
tubes and components were employed
in the manufacture of this equipment.
Individual illuminated VU (Volume
Unit) meters were provided for each
recording and reproducing channel as
well as individual gain controls.

A unique problem in the design of this
unit arose due to the necessity for pro-
viding an overall or master gain control
which controlled simultaneously the
gain of both channels. This was ac-
complished through the use of a special
dual potentiometer with matched rota-
tional ohmic accuracy in the order of
plus or minus 5%.

Provision was made for headphone
monitoring from the front panel of the
amplifier through the use of specially
built Permoflux binaural headphones
having an effective response to over
12,000 cycles/sec. These headphones
are provided with large foam-rubber
ear cushions in order to exclude ex-
traneous noise and to reduce the well-
known head fatigue that comes from
the use of ordinary earphones. Dual
monitor speakers close together on a
small panel would not yield any useful
binaural effect and might be dangerously
confusing for monitoring use. There-
fore, in addition to the binaural head-
phones, a single small monitor speaker
is provided behind a flocked screen
panel on the front of the amplifier. A
unique control is included for this
speaker which is so arranged that it is
"off" when set at its center position.
Maximum volume for one channel is
obtained by turning the control to the
extreme right, and maximum volume
for the other channel, by turning the
control to the extreme left.

The amplifier tube lineup for a single
amplifier channel consists of two 5879
tubes followed by a dual triode 12AX7,
the second half of which is used as an
inverter driving a pair of push-pull
6AQ5 tubes. The same amplifier is
used for playback as well as recording.
A multiple section (shielded between
sections) ganged selector switch is used
to switch equalizer and gain functions
for the dual amplifiers when changing
from the record to playback positions.
In order to provide freedom from hum
in the low-level stages of the amplifiers,
direct current is used on the filaments of

Otto C. Bixler: Binaural Recorder

113

BlNAURAL RECORD - PLAY BACK
FREQUENCY RESPONSE

OK BJTfOK

FREQUENCY- IN CYCLES PER SECOND
Fig. 2. Overall 15-in./sec tape speed, record-reproduce frequency response.

the input tubes. This is derived from a
full-wave selenium rectifier.

The output of the playback system
consists of two independent 10-w ampli-
fiers with nominal output impedance
of 4 and 1 6 ohms. A 600-ohm balanced
connection is also provided at a line
level of +4 dbm for each channel. The
system is both pre- and post-equalized
in order to achieve a flat response at
15 in./sec recording speed of from 50
cycles to 15 kc ± 2 db (Fig. 2). Both
the amplifier unit and the tape transport
are provided with facilities which allow
operation at 7-g- in./sec with a frequency
response of from 50 cycles to 7.5 kc ±
2 db.

A signal-to-noise ratio in the order of
50 db is achieved with this equipment.
The residual crosstalk between channels
is essentially due to low-frequency
magnetic coupling below 100 cycles/sec.
This crosstalk measures approximately
35 db at 50 cycles and drops with fre-
quency increase until it goes below the
tape noise level at a little over 100
cycles/sec.

Calibration Means

In order to assure accurate localizing
based upon binaural amplitude com-

parison, it is desirable that all possible
electronic balancing between the two
record-reproduce channels be carried
out. To this end, a calibration button
is provided which inserts a 60-cycle/sec
signal simultaneously into the first
stages of both amplifier inputs. The
channel gain controls may then be
individually adjusted to obtain equal
VU meter readings. The balanced
signals may then be recorded if the tape
transport is turned on. When played
back, the two 60-cycle signals may
again be read on the VU meters and the
playback gain controls may then be
balanced for the optimum binaural
effect.

Commercial Applications

The design of this equipment was
aimed at satisfying certain specific
commercial applications although it
has a definite application to high-
fidelity music recording-reproducing,
where listening pleasure is desired to
be as high as possible. The majority
of commercial applications lie in the
field of identification of intelligence or
information where it is necessary to
distinguish between each of many

114

August 1952 Journal of the SMPTE Vol. 59

Fig. 3. Binaural recorder in field use by auto manufacturer testing for noise.

sound sources which may be spread
around a given area.

Court recording is one very important
and useful application of this equipment.
With it, accurate records including
differentiation between the various per-
sons in a courtroom may be made.
A study by Ray Hirst6 of monaural
court recording has shown that too
often court records are at variance
with what actually transpired because
the court clerk was unable to follow
testimony fast enough to accurately
transcribe data as it was presented; or
because the clerk heard something wrong;
or because the clerk simply made a
mistake. On one occasion, to our
knowledge, it was necessary to reverse
the written record due to a stenographic
error. Application of this equipment
to a Court of Justice would help to
improve the carrying out of justice.
We have carried out courtroom tests
with very effective results and have
some excellent demonstration tapes.

Another application of this binaural

technique is that used by police^and
secret-service departments for secret
recording of conversations. The stand-
ard accepted methods of masking a
voice's intelligibility are by the use of
continuous tapping noise, by the run-
ning of faucet water or by the turning
up of a radio for background masking
noise. A monaural system cannot dis-
tinguish between the masking noise
and the intelligence it is desired to
detect. A binaural system localizes
the attempt at masking and allows the
listener to associate direction with the
desired sound so that he may achieve
intelligibility.

Business, technical or military con-
ference proceedings are a natural for
this type of recording since the data
may later be transcribed by a stenog-
rapher with considerable freedom from
error caused by simultaneous talking
or masking. A stenographic transcrip-
tion may be made of two people talking
simultaneously since by mental localiza-
tion the stenographer may concentrate

Otto C. Bixler: Binaural Recorder

115

on the speakers one at a time and then
play back the recorded material a
second time to get the second speaker.
In some recently conducted tests it was
found that if two conversations are
simultaneously recorded, a capable
operator can produce an accurate
transcription even when the desired
conversation was recorded at a 13-db
lower level than the unwanted dialogue.

In radio and motion picture work the
second recording channel may be used
as a cue or control track for special
effects or for recording commentary
along with the primary intelligence.

In the laboratory or for field-test
work the binaural equipment may be
used for recording either binaural or
dual-track test data for later careful
analysis. Figure 3 shows a binaural
recorder in field use by a prominent
automobile manufacturer. Note that
this setup shows the predecessor to the
dual-channel amplifier unit.

The field of audio-visual education
utilizes realism as a teaching aid. This
portable binaural packaged system
readily lends its "third-dimensional"
sound reality to assist in critical analysis
of band or choir practice, speech classes,
dramatics, etc.

Conclusion

1 . No appreciable sacrifice in quality
from that of a standard ^-in. tape re-
cording system was necessary in these
units.

2. The resultant equipment as manu-
factured is really of a portable nature
and is housed in two carrying cases.
The amplifier unit weighs but 37 Ib,
while the tape transport has a weight
of 29 Ib.

3. From the foregoing data, it is
apparent that the design objectives of
producing a practical but low-cost
commercial binaural record-reproduce
magnetic tape equipment were accom-
plished.

References and Bibliography

1. Stereophonic Sound-Film System, a sym-
posium of seven papers presented May
1941 at the Spring Meeting of the
SMPE at Rochester, N.Y. Published
as Bell Telephone System Monograph
B-1327, 1941; and in Jour. SMPE, 37:
331-426, Oct. 1941; consisting of:
H. Fletcher, "General Theory";

E. G. Wente, R. Biddulph, L. A. Elmer
and A. B. Anderson, "Mechanical
and optical equipment for the stereo-
phonic sound-film system";

J. G. Steinberg, "Pre- and post-equali-
zation of compandor systems";

W. B. Snow and A. R. Soffel, "Electrical
equipment for the stereophonic sound-
film system";

E. G. Wente and R. Biddulph, "Light-
valve for the stereophonic sound-film
system" ;

E. G. Wente and A. H. M{Uler, "In-
ternally damped rollers";

L. A. Elmer, "A non-cinching film re-
wind machine."
Note: The first three of the above

papers were published also in /. Acoust.

Soc. Am., 13: 89-114, Oct. 1941.

2. H. Fletcher, "Auditory patterns," Revs.
Modern Phys., 12: 47-65, Jan. 1940.

3. Wire Transmission of Symphonic Music
and Its Reproduction in Auditory Per-
spective, a symposium of six papers pre-
sented at the Winter Convention of
AIEE, Jan. 1934. Published as Bell
Telephone System Monograph B-784,
1934; in Elec. Eng., 53: 9-32, 216-218,
Jan. 1934; and Bell System Tech. /.,
13: 239-310, Apr. 1934; consisting of:
H. Fletcher, "Basic requirements";

J. C. Steinberg and W. B. Snow,
"Physical factors";

E. G. Wente and A. L. Thuras, "Loud-
speakers and microphones" ;

E. O. Scriven, "Amplifiers";

H. A. Affel, R. W. Chesnut and R. H.
Mills, "Transmission line";

E. H. Bedell and Iden Kerney, "Systei
adaptation."

4. Lorin D. Grignon, "Experiment
stereophonic sound," Jour. SMPE,
280-292, Mar. 1949.

5. J. P. Maxfield, A. W. Golledge and
T. Friebus, "Pick-up for sound moti(
pictures (including stereophonic)," Jo
SMPE, 30: 666-679, June 1938.

116

August 1952 Journal of the SMPTE Vol. 59

6. Ray Hirst, unpublished work on court
recording, (Eugene, Oregon) Official
Court Reporter, 2nd Judicial District,
State of Oregon.

Discussion

R. H. Ranger (Rangertone, Inc.) : Through
the courtesy of the Magnecord Company,
I have had the privilege of using one of
these equipments and I want to say that
it is certainly most intriguing to have the
opportunity to do so. The particular
reason they were anxious to have me try
it was to see if we could record a syn-
chronizing signal on this same tape and I
can report to you people who are obviously
very interested in synchronizing that it
is quite feasible. We have recorded the
longitudinal track in the center between
the other two tracks, so that you can get
synchronous operation using this binaural
equipment.

I might just add one little reaction that
I have had with it and which I confirmed
with Dr. Fletcher just yesterday in New
York, and that is that not only is it in-
teresting to get two speakers differentiated
spatially by this process, but the actual
quality of a single speaker, a single person
singing, or a single instrument seems to be
improved. As Dr. Fletcher said, "I'm
too old to figure that out. We'll have to
leave that to the younger people."

Anon: Is there any provision in your
equipment for playback on one channel
while recording on the other?

Mr. Bixler: No, there is not at the present
time.

Anon: I have asked that only because
there are several applications for which
I think that would be a very useful feature.
One of them, for instance, is prescored
accompaniment in music, while the person
! practices his solo beside it.

Mr. Bixler: I might say that there is a
single multiple contact selector switch
which is used to switch both channels
simultaneously from record to playback,
and that you could do what you suggest
if you were to go into the circuit and build
in two switches, in place of this single
switch along with seme other minor
modifications.

C. H. Lankester (United Nations) : In
view of the fact, as I understand it, that

there is a longitudinal displacement be-
tween the record heads, have you found it
possible to standardize a positioning of
the two heads perfectly accurately, that
a binaural recording made on that recorder
would play back on another without loss
of the binaural effect?

Mr. Bixler: I might say that the speed
of the tape actually helps in this respect
because it's relatively fast and each wave-
length covers quite a bit of tape when
you "lay" down the signal. On the
other hand, heads are supported in fixed
castings so that these same patterns are
used in all our machines — it's the stand-
ard casting we've been using for years,
so that insofar as our equipment is con-
cerned, the location of the heads auto-
matically falls in identically the same
position in each and every machine. If
there is some minor spacing difference
the speed of the tape is sufficiently great
so as to swamp that difference out.

John G. Frayne (Westrex Corp.): I would
like to ask Mr. Bixler if he found it im-
possible to put the two separate heads
in the same head structure because the
crosstalk between them would then be
undesirable.

Mr. Bixler: Well, yes and no. I imagine
if we had tried to put them right alongside
of each other we would have had some
crosstalk and I looked with interest at
Charlie Davis' disclosure in a recent
SMPTE Journal., but it was a matter of
expediency in utilizing present equip-
ment and space location on existing
castings on which, as I mentioned, we
simply replace the existing record and
reproduce monitor heads in standard
equipment. Thereby it turns out that
the heads are spaced from about one-half
to about three-quarters of an inch apart
automatically.

Dr. Frayne: What is the separation now
between the two half-tracks — between
the two components, rather, approxi-
mately?

Mr. Bixler: I don't know.

John Boyers (Magnecord, Inc.) : 50 thou-
sandths of an inch.

Mr. Bixler: Thank you, John.

Dr. Frayne: I believe that with about
50 thousandths separation you might work
in the decoupler such as Davis discloses.

Mr. Bixler: Yes, that is if we had heads
that were suitable for that type of mounting.

Otto C. Bixler: Binaural Recorder

117

Follow-Focus Device and Camera Blimp
for 16mm Professional Camera

By LEE R. RICHARDSON and WILLIAM N. GAISFORD

A novel system of lens focusing, coupled with a synchronized parallax correc-
tion cam and focusing viewfinder, is accomplished by the use of planetary
gearing to the lenses which also permits fast shifting of lenses without dis-
engaging any cams, gears or footage dials. A plastic camera blimp for the
16mm professional camera and follow-focus mechanism is introduced which
reduces the noise level to permit professional sound cinematography.

A RODUCERS OF 16mm television and
industrial films are frequently con-
fronted with the problem of photo-
graphing a live show, sporting event or
other unrehearsed productions which
cannot be repeated. In many instances
when filming these shows, it is necessary
to follow a moving subject which may
move toward or away from the camera
making it necessary to keep the subject
in proper focus and suitably composed
on the film. Further, a camera blimp
is often required which will reduce the
noise level of the camera to permit
sound recordings under the most critical
sound conditions.

The Raphael G. Wolff Studios of
Hollywood, producers, of television and
commercial productions, were faced
with problems similar to the above.

Presented on April 25, 1952, at the Society's
Convention at Chicago, 111., by Benjamin
Berg for the authors, Lee R. Richardson
and William N. Gaisford, Richardson
Camera Co., 1065 N. Fairfax Ave., Holly-
wood 46, Calif.

After consultation with the Richardson
Camera Co., they submitted specifica-
tions for a follow-focus device and
camera blimp for a Maurer 16-05 Pro-
fessional Camera equipped with 15-mm
//2.5, 25-mm //1 .4 and 40-mm //1. 4
Eastman Cine Ektar lenses.

The Wolff Studio's specifications called
for the development and manufacture
of a mechanism to permit follow-
focusing of each lens of a multiple-lens
turret through their focusing range
(3 ft to infinity), provide a simple and
efficient means of shifting to another
lens of a different focal length at any
time, maintain the same focus setting
as the preceding lens without interfering
with the functions of racking over the
camera or threading the film in the
camera and enable the operator to keep
subjects constantly in sharp focus and
suitably composed on the film as the
distance between subject and camera
position varies even though the subject
may move away from or toward the
camera in a direct line or at an angle.

118

August 1952 Journal of the SMPTE Vol. 59

The requirements of the blimp were
to contain the camera and follow-focus
mechanism and be constructed of a
sound deadening material, be light-
weight, and reduce camera noise inter-
ference to a level permitting the use of a
microphone within 3 ft of the camera.

The Maurer Camera was ideally
suited to this project as it comes equipped
with a focusing viewfinder with a
parallax compensating mechanism.

Design and Construction

A planetary system of gearing was
selected as it made possible the functions
of keeping the entire gear driving mech-
anism and viewfinder linkage per-
manently engaged. The fact that all
three lenses are caused to rotate simul-
taneously in their mounts is not objec-
tionable (Fig. 1).

Each lens was set up in a dividing
head and the amount of rotation from
the 3 -ft mark to the infinity mark were
obtained in order to determine the
correct gear ratios for synchronizing the
lens calibration with the focusing dial
and control knob.

The main drive gear consists of a ring
gear having both internal and external
gear teeth of 48 pitch with annular
ball races ground on both faces of the
gear and loaded with 480 -jVin. steel
balls. Two retaining gear rings are
grooved to match the ball races which
hold it in place on the front of the camera
case. The balls are slightly preloaded
to allow the ring gear to rotate with
minimum friction and no end play.

Compound gears of proper ratio are
driven by the internally cut teeth of the
ring gear and are ball-bearing mounted
on fixed stud shafts attached to the lens
turret plate. These gears in turn mesh
with the ring gears attached to the lens
focusing barrel.

A gear transfer case transmits motion
from the control knob and dial assembly
to the externally cut teeth on the ring
gear and also to a master cam plate
gear housed in the subbase of the

camera. These two gears are syn-
chronized with a ratio of one to one.

The master cam plate has three scrolls
(Fig. 2) each generated and cut to act
upon a cam follower and linkage to the
Maurer focusing viewfinder. The cam
is spring loaded against the scroll to
eliminate backlash.

The viewfinder was modified to func-
tion with a minimum of friction and
backlash by removing the rack and
pinion and replacing the dovetailed
slides with ball rollers. As the Maurer
viewfinder has two parallax compensat-
ing cams, one for the wide-angle lens,
15-mm, and the other for the 25-mm
and 40-mm lenses, an adjustable link-
age was provided for manually shifting
the finder only for the wide-angle lens.

The control knob and dial assembly
is one detachable unit and can be
mounted on either the left or right side
of the camera. A splined coupling
permits engaging the control unit to
several reading angles.

Operation

A simplified sketch is shown (Fig. 3)
which illustrates the basic principle
involved in the operation.

Control knob (a) drives gear (b)
which in turn rotates internal ring gear
(c) causing gears (d, e, f) to rotate, in
turn causing gears (g, h, i) to revolve,
By proper gear ratios, (g, h, i) rotate
lens focusing barrels (j, k, 1); thereby,
keeping all lenses synchronized in
respect to their focusing range from
infinity to their nearest focal point.
When lock (n) is released from notch
in turret plate, and control knob (a) is
rotated in either direction, the entire
lens-mount assembly attached to the
mounting plate (m) will rotate until
by-pin (n) drops into next indexing
notch in plate (m). All lenses will
remain in the same synchronized focus
position as the lens mount assembly is
shifted from one lens to another because
the resistance of the lens-focusing barrels
and the gearing will overcome the lighter

Richardson and Gaisford: Focus Device and Blimp

119

Fig. 1. Planetary gearing system to lenses.

120

Fig. 2. Master cam plate and viewfinder linkage.
August 1952 Journal of the SMPTE Vol. 59

Fig. 3. Schematic drawing of basic principle of planetary gear system.

friction of the mounting plate (m). In
shifting from one lens to another, the
focus dial (o) will rotate one complete
revolution thereby returning to the same
distance calibration as the preceding
lens.

Example: In the case of a three-lens
turret assembly, as illustrated, the gear
ratio between the control knob (a) and
the internal ring gear (c) is 3 to 1 with
three indexing notches on the lens
turret plate, one to index each of the
three lenses. Focus dial (o) will rotate
one complete revolution in shifting
lens-mount assembly to next lens. This
will allow the use of only one focus dial
for all three lenses.

The follow-focus operation incor-
porates, in addition to the foregoing
system of lens focusing, a method of
actuating the focusing viewfinder so
that the optical elements of the finder

sharply focuses the image on its viewing
glass in synchronization with the lens
focusing of the image on the film.

A stop pin within each lens mount
prevents the lenses from rotating beyond
their infinity position. This in turn
prevents the control knob from being
further rotated due to the lens turret
plate assembly being locked by the
turret locking pin. When a release
button is pressed and the control knob
turned, the entire lens turret assembly
rotates until the next lens is in place,
indexed and locked by the turret locking
pin. Synchronized with this function is
the cam follower which rides out of its
cam scroll into an inclined circular
groove and drops down into the next
cam scroll and is synchronized to the
next lens that comes into place.

The linkage from the cam follower
to the focusing viewfinder is so con-
structed to permit racking over the
camera for lining up a scene and also

Richardson and Gaisford: Focus Device and Blimp

121

Fig. 4. Three-quarter front view, showing window over camera lens.

for opening the camera door to rethiead
the film. The viewfinding actuating
cam scrolls were generated to their
respective lens-focusing distances at the
full lens opening. The depth of the
field of the lenses allows for normal
human error in follow-focusing on a
moving subject or when the camera is
mounted on a moving platform in rela-
tion to a fixed subject.

Camera Blimp Design and Construction

The component sections of the blimp
(Figs. 4 and 5) were designed to take
advantage of the simplified method of
fabrication which is possible with
Royalite Plastic, a product of the U.S.
Rubber Co.

The base and cover sections are
reinforced with an aluminum frame
giving additional strength and support
for the cover hinge. The interior of
the blimp is further soundproofed with
Royalite expanded plastic and finished
off with a corduroy covering. A rubber
grommet, around the edges of the lower
part of the blimp, acts as a seal when
the cover is closed. The camera mount-

ing base is a steel plate cemented
the inner base of the blimp with
|-in. thick pad of neoprene spon
rubber between. Guide rails are
tached to the base plate to register t
camera when installing in the blim
An aluminum alloy plate is rubbe
bonded to the bottom of the blimp
providing a firm support for the entire
unit when mounted on a tripod, camera
dolly or platform.

Other main features of the blimp are:
(1) an optical glass window which
hinged permitting access to the lenses
for setting / stops; (2) portholes for
observing /-stop markings when blimp
cover is closed and to check on magazine
take-up wheels; (3) external control
for turret release button; (4) pilot light
to illuminate the interior of the blimp
when making lens adjustments, thread-
ing, etc.; (5) jeweled indicator lights
which show when camera motor is
running and pilot light is on; and (6)
windows in the rear of blimp for looking
through viewfinder, checking shutter
openings and footage counter.

122

August 1952 Journal of the SMPTE Vol. 59

Fig. 5. Side view, showing control knob and dial assembly.

Comments

The Richardson Camera Co., when
designing the lens-focusing system, were
aware of the discrepancies between the
three lenses. The problem, however,
was not to construct an absolutely ac-
curate focusing system as would be
required on precision optical printers
but to provide an efficient, simple and
quick method of follow-focusing for the
cinematographer on action shots.

In focusing a lens on a variable mov-
ing subject, it is necessary for the camera
man or his assistant to estimate or
determine by some visible means the
distance between the camera and sub-
ject. He must then transfer this in-
formation to the lens-focusing control
knob or footage dial all of which in-
volves a human function with limited
accuracy. The depth of focus of the
lens in use is intended to permit a

Richardson and Gaisford: Focus Device and Blimp

123

certain amount of error in the judgment
of the operator.

The designers increased the accuracy
of the mechanism by calibrating the
footage dial to the longest focal length
lens used, 40-mm at //1. 4 stop. Ob-
viously, where critical focusing is re-
quired, the camera is racked over and
the subject aligned and focused on a
ground glass. This is the most accurate
means of focusing and does not depend
on footage calibrations engraved on the
lens. This means of focusing cannot
be used when the subject or camera is
in motion.

Conclusions

The follow-focus device was found
to be exceedingly efficient as to the
accuracy of the mechanism and as to
simplicity and time-saving in operation.
The knowledge that the lens parallax
and distance calibrations are at all times
synchronized gives, to the operator,
assurance that a sharp focused and
composed image is properly recorded
on the film.

The lightweight plastic blimp was
tested on i sound stage under normal
operating conditions and found to be
equal in performance to other blimped
professional motion picture cameras.
In most cases, the front glass was left
off and still the camera noise was below
the ambient sound noise of the stage
making it possible to record dialogue
with the microphone within 3 ft of the
camera.

Acknowledgments

The authors wish to acknowledge the
sponsorship of this project by the
Raphael G. Wolff Studios, to Mr.
Wolff personally and his camera tech-
nicians Art Treutlaar, Gail Papineau
and Henry J. Ludwin, all of whom
outlined the essential requirements in-
corporated in this design. Charles L.
Bluske, industrial designer, styled the
camera blimp. John Roy of the U.S.
Rubber Company gave technical advice
on fabricating Royalite Plastic material.
The Glen Glenn Sound Co. gave its
sound stage facilities for testing the
performance of the equipment.

124

August 1952 Journal of the SMPTE Vol. 59

Instantaneous Theater Projection
Television System

By VICTOR TRAD and RIGARDO MUNIZ

A new, inexpensive, instantaneous dual theater projection television system
of the Schmidt type is described. A simple control box providing almost
instantaneous change-over, in the event of breakdown, and mechanical
arrangements facilitating ease of installation and maintenance are discussed.

STUDY of the needs of the motion
picture theater owner and operator
made over a period of many years, in
connection with the development of this
and earlier projection television units,
has revealed the need for a thoroughly
satisfactory and reliable theater pro-
jection television unit which will, at
the same time, be substantially lower in
cost than those others currently available,
and which will be amenable to relatively
simple installation techniques, and which
can be supplied and kept in adjustment
easily by the motion picture projection
machine operator. This paper pre-
sents some of the technical and opera-
tional features of the present Trad
theater television unit.

It will be seen that, in this typical
installation (Fig. 1), the Trad dual
unit rests upon a simple support bracket

Presented on April 21, 1952, at the Society's
Convention at Chicago, 111., by Frank H.
Riffle for the authors, Victor Trad and
Ricardo Muniz, Trad Television Corp.,
1001 First Ave., Asbury Park, NJ.

which, in turn, has been attached to the
main balcony support of the theater.

This places the unit in the proper
operating position with respect to the
theater screen, and also provides maxi-
mum accessibility from the balcony of
all adjustments and chassis for routine
operation and maintenance.

Figure 2 shows how the two chassis,
the low-voltage power supply with
video amplifier and the high-voltage
sweep chassis, are mounted with rela-
tion to the projection optical system,
and also how accessible the units can
be from the balcony without the use of
ladders or scaffolding.

The various electronic adjustments
are located in the rear of the high-
voltage sweep chassis and, once made,
need be checked only at infrequent
intervals, but which are conveniently
accessible from the balcony since they
are on the side of the chassis nearest
the balcony. It is important to note
that this is the only place in the entire
installation where any high voltage
exists. It is not necessary to have
elaborate high-voltage transmission sys-

August 1952 Journal of the SMPTE Vol. 59

125

Fig. 1. A theater installation, showing the dual unit mounting

terns nor protective devices with the
Trad theater television unit.

The remote-control unit (Fig. 3) is
mounted in the motion picture pro-
jection booth near one of the port holes.
This remote-control unit provides for
the adjustment of contrast, vertical and
horizontal hold, and also for the switch-
ing from one of the dual units to the
other, in the event that any trouble
develops in the one in operation. It is
here that the operator stations himself
and it is these^ controls alone which he
will find it necessary to manipulate
during the normal operation of the
equipment.

Signals are provided by a monitor,
Fig. 4, containing a television receiver
and providing video amplification for
any remote programs from either
microwave link or the coaxial cable.

It also provides a third service in that
the television receiver which it contains,
when connected to a suitable antenna,
can provide off-the-air signals from local
television broadcasters, should these
be required.

Getting back to the main unit. Figs.
5A and 5B show some of the unique
features which have resulted from the
long practical experience with this type
of device. The patented Trad theater
projection television unit was designed
not only from the standpoint of opera-
tional simplicity but also to project the
greatest possible amount of light from
the projection tube to the screen.

As can be seen, the obstacles to the
reflected rays of light have been mini-
mized. It is interesting to note that,
with a mirror diameter of 14 in. and
a focal length of 6.6 in., the effective

126

August 1952 Journal of the SMPTE Vol.59

Fig. 2. Close-up of one side of the unit, with protective
hood open.

Fig. 3. Remote-control unit. Fig. 4. The monitor.

Trad and Muniz: Theater Television System 127

aperture of the Schmidt optical system
used is//0.85.

- _ focal length
effective diameter

6.6 in.

7.77

0.85

Light-meter readings taken at the
surface of the corrector plate are 160
ft-c. The optical barrel provides for
adjustments of vertical and horizontal
centering, conveniently accessible from
the balcony by swiveling and tilting
the barrel, and also for overall top-to-
bottom optical focus. The convenience
of these adjustments can be readily
appreciated by any user who has at-
tempted to make these adjustments on
other types of television projection
barrels.

It will be noted in Fig. 5A that the
vertical and horizontal focus adjust-
ments are accomplished by moving the
"dish," which is the curved-front sur-
faced reflector in the optical barrel,
vertically or horizontally by screw-
operated mechanisms controlled by the
two knobs shown for each direction.
Similarly, as in Fig. 5B, the optical
focus control has been brought forward
by mechanical means so that a simple
knob within easy reach of the balcony
is all that need be controlled. In
installations having the optical system
higher than the center of the theater
screen it becomes necessary, of course,
to tilt the barrels downward in order
to throw the picture within the dimen-
sions of the screen. In doing this it is
found that, if the optical focusing
adjustment is carefully set for the center
of the screen, the top and the bottom
of the picture are somewhat out of focus.

By adjusting the vertical and hori-
zontal focus adjustment knobs in the
rear of the barrel, the picture can be
brought into good overall focus without
having to tilt the screen. A high degree
of "practical" engineering has gone
into the Trad barrel as a result of many

years of acrobatic hanging by one foot
from theater roofs, perching on the top
of fire-engine ladders or chinning one-
self on a trapeze while using the teeth
for adjustment purposes. So, here now
is a barrel which doesn't require an
acrobat, or any unusual courage or
skill to operate. It may be noted in
passing that there is symmetry about
the center of the dual unit, with the
left-hand and right-hand units being
mirror images. Each of them inde-
pendently provides all of the necessary
adjustments in equally accessible form.

There are three unique technical
features worthy of attention: (1) the
high-voltage multiplier supply; (2) the
automatic brightness control; and (3)
the video amplifier response characteris-
tics. Taking these in order:

The high-voltage tripler operates on a
very interesting principle. Figure 6 is
a simplified schematic showing the
operation of the voltage multipliers.
It will be noted that the 6BG6 tube
shown in the diagram is one of the
horizontal deflection amplifiers which
supplies the proper waveform of current
to the horizontal deflection coils, which
cause the electron beam to scan the face
of the cathode-ray tube horizontally
during operation. At the end of each
horizontal line, the 6BG6 plate current
is "cut off" after the incoming hori-
zontal sweep signal drops to zero. A
positive pulse of voltage appears at
point A as a result of the collapsing
field of the horizontal deflection coil
(this is a kickback or flyback voltage).
These positive pulses are first rectified
by VI which is a diode vacuum tube,
and the capacitor Cl is found to be
charged to a value very near the peak
value of the original pulse. Since the
cathode of VI is connected to the plate
of V2 through Rl , then C2 will charge
up to the same voltage as Cl. The
charge on C2 is thus added to the
oncoming pulse and tube V2 rectifies
the sum of these voltages, thus charging
capacitor C3 to double the original pulse

128

August 1952 Journal of the SMPTE Vol. 59

Figure 5A. Figure 5B.

Views of the optical barrel.

VI £ftl V2 <R2 I 1V3

Fig. 6. Simplified diagram of the high-voltage tripler.

Fig. 7. Simplified diagram showing Rl and R2 replaced by V4 and V5.

Trad and Muniz: Theater Television System 129

voltage. The charge on C4 is added
to the already duplicated incoming
pulse voltage and V3 rectifies this po-
tential to produce a charge on capacitor
C5 of three times the incoming pulse
voltage. In the case of this unit, the
original pulse voltage is somewhat over
10,000 v so that the output of the volt-
age multiplier system is approximately
33,000 v.

The type of voltage tripler which was
just described is conventional and is used
on some other types of television pro-
jection devices; however, practical ex-
perience has shown that Rl and R2
have such high voltage gradients that
it is next to impossible to obtain re-
sistors which will have long life and
which will retain resistance stability
for a reasonable period. Therefore,
in the interests of maximum reliability,
these resistors have been replaced in
the Trad unit by two additional high-
voltage diode rectifier tubes V4 and V5,
as shown in Fig. 7, functioning as
thermionic resistors and having longer
life and greater stability. This was
possible because the high voltage across
the resistors was direct current; therefore,
the vacuum tube could be connected
in such a manner that it would present
a high impedance to voltages of that
polarity while permitting currents in
the reverse direction to flow with rela-
tive ease. Thus the vacuum tube
provides a higher inverse resistance than
would have been practical with re-
sistors and still have the advantage of a
low impedance in the reverse direction.

Figure 8 shows this circuitry embodied
in a completely enclosed plastic housing
which provides large margins of safety
with respect to arc-over or strike-over
of high voltage between the circuit
elements and/or ground. The simple
and clean design which has been
achieved can readily be seen in this
high-voltage unit. It is interesting to
note also that the five-tube tripler unit
can be readily removed from the balance
of its circuits for routine maintenance,

and that this construction also pro-
vides the maximum ease of replacement
in the event of any form of failure in the
unit.

In Fig. 9, the capacitors Cl, C2,
C3, C4 and C5 can readily be seen.
It should be noted that there are no
wires or other protuberances in the
high-voltage compartment which would
induce breakdowns.

Figure 10 shows the actual circuitry
in the high-voltage and sweep chassis.
The circuit diagram shown herewith is
fairly conventional, but may be worthy
of a few words. The composite video
signal has had the synchronizing in-
formation stripped from it in the asso-
ciated low-voltage power supply unit,
shown in Fig. 11. This synchronizing
information is fed into the unit shown
and separated into both horizontal
and vertical synchronizing pulses by the
6SN7 vacuum tube. A blocking type
of oscillator is used for the vertical
deflection, whereas a synchro-lock type
of horizontal oscillator circuit for maxi-
mum synchronizing stability is used for
the line frequency. The five-tube trip-
ler, which was explained above, is seen
in this diagram, together with its asso-
ciated circuitry.

Figure 11 is the schematic circuit
diagram of the low-voltage power supply
and video chassis. It will be noted, a
two-stage video amplifier with series
and shunt peaking is provided, and that
a d-c restorer of conventional design
as well as a synchronizing stripper are
incorporated on this chassis. The un-
conventional part of this unit is given on
the right-hand side of the d-c restorer
tube which, with its associated circuitry
shown herewith, rectifies the video
signal which appears across the plate
load resistor of the second video ampli-
fier stage and supplies this potential to
the accelerator grid of the picture tube.
This portion of the d-c restorer and its
associated circuitry is an automatic
brightness control.

130

August 1952 Journal of the SMPTE Vol. 59

Fig. 8. The tripler assembly, top.

Fig. 9. The tripler assembly, bottom.
Trad and Muniz: Theater Television System

131

JF I Al

Fig. 10. Circuitry in the high-

The automatic brightness control
circuit, Fig. 12, is a means of auto-
matically adjusting brightness on a
cathode-ray tube, utilizing the varying
plate voltage of the video output tube
to adjust automatically the accelerator
voltage on the accelerator grid AG of
the cathode-ray tube CRT.

This automatic adjustment not only
maintains the greatest amount of high-
light brilliance at any amount of video
signal input, but also prevents the
cathode-ray tube from blooming, that is,
it prevents abnormal enlargement of
picture or raster. This in effect is
accomplished by varying the accelerator

132

August 1952 Journal of the SMPTE Vol. 59

voltage and sweep chassis.

voltage upward when the video signal
is increased and downward when video
signal is decreased.

If the automatic brightness circuit is
not used, and a high fixed voltage is ap-
plied at AG at greatest video signal
input, the highlight brightness of the
image is high; but upon decreasing the

video signal, the brightness of the raster
remains the same and the high voltage
at HV decreases gradually until the
signal is removed. Then the raster
"blooms" and becomes "milky," and
the high voltage at HV shoots up to its
maximum, possibly causing arc-over
in the system.

Trad and Muniz: Theater Television System

133

*i pf

Fig. 11. Circuit diagram of the low-

If, on the other hand, a low fixed
voltage is applied at AG at the greatest
signal input, the highlight brightness is
not as high as when the above automatic
circuit is used, but the voltage at HV
is at a higher point than above. Then,
upon decreasing the video signal, the
high voltage decreases and the raster
brightness remains the same — even
after the signal is removed.

From the two conditions described,
it is found that, at the high signal input,
the picture should be brightest; there-
fore, the volts at AG should be at a
maximum. This keeps voltage at HV
at a fixed high-voltage point for greatest
possible highlight brightness. As the
signal is decreased, the voltage at AG
should be decreased, so that the voltage
at HV remains very close to its high-

134

August 1952 Journal of the SMPTE Vol. 59

MALE BANANA PLUS
TO HIGH-VOLT. CHASSIS

voltage power supply and video chassis.

voltage point, giving the brightest
possible picture at this setting. Upon
the removal of the signal, the voltage
at AG should be brought to its lowest
point for proper operation to prevent
blooming and the voltage at HV con-
tinues to decrease normally — prevent-
ing the failures and breakdowns as
explained previously. Also, it is readily
seen that changing from station to station

in this system will cause a decrease of
voltage at HV making a very effective
safeguard against breakdown.

Potentiometer R, Fig. 12, is a manual
adjustment of this proper minimum and
is used to compensate for variables in
different units which may cause this
minimum voltage to be too high, thus
causing blooming and the shooting up
of the voltage at HV.

Trad and Muniz: Theater Television System

135

Fig. 12. Automatic brightness control circuit.

The use of a manual brightness control
would satisfy the necessary conditions
for optimum picture performance, but
the addition of another control for the
operator to set tends to make the
operation of the unit a bit more com-
plicated. The ideal condition is to
eliminate the use of manually operated
controls and obtain optimum per-
formance settings automatically. The
"Trad" automatic brightness control
circuit described above accomplishes
this with a high degree of efficiency.
This system, in addition to being an
automatic brightness control, is also an
automatic high-voltage regulator keep-
ing the voltage safe at the varying input
signal levels.

The graphs in Fig. 13 reveal the
action of the automatic brightness
control with varying video inputs. Also,
shown in Fig. 14 is the interrelationship
of average beam current resulting from
the effect of the automatic brightness
control as the video signal is varied.
These graphs were made using a flying-
spot scanner picture generator, and
varying the output signal voltage, going
from no picture, through all the inter-
mediate stages, to a condition of maxi-
mum contrast.

One of the important design features
of the Trad theater projection television
unit is the picture quality, which is the
result of critical peaking of the video

amplifier circuits to produce a picture
of maximum crispness without ringing
or smearing. It will be noted from the
curve in Fig. 1 5 that the usable response
has been extended to approximately 7
me, being more than adequate for clear
and crisp picture reproduction from
either closed-circuit or off-the-air opera-
tion.

No less important to the theater
owner and operator is the low cost and
relative ease of installation of this
equipment. Surveys of many theaters
were made before design decisions were
arrived at, with the result that much
less special work need be done in the
theater during the installation of this
equipment than many others currently
offered.

It will be noted, in referring to Fig. 1,
that associated dual video amplifier,
sweep, and high- and low-voltage supply
chassis are installed in a convenient-
sized housing which is supported at the
fore part of the balcony on a single
fabricated bracket which is supplied
by Trad. This bracket is mounted by
means of bolts through the structural
support in the balcony. When mounted
in this position, it is out of harm's way
and yet is readily accessible for routine
maintenance and adjustment.

Figure 16 shows the simplicity of the
complete electrical wiring of the system,

136

August 1952 Journal of the SMPTE VoL 59

ft 20 40 60 80 10

zzo

210
200
190
180

220

AUTOMATIC
MANUAL B

BRIGHTNESS
IGHTNESS (

OPERATION
PERATION

ACCELERATOR GRID VOLTAGE^

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STMENT TO
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ATION.

UIRED
MAINTAIN
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170

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160

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COMPOSITE VIDEO VOLTAGE R TO P.

Fig. 13. Accelerator grid voltage vs. composite video voltage, peak to peak.

0 20 40 61

D 80 1C

0
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I.C
.8

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COMPOSITE VIDEO VOLTAGE R TO P.
f. 14. Average anode beam current vs. composite video voltage, peak to peak.

Trad and Muniz: Theater Television System 137

ion

IOOKC 400KC IMC !

3 4 56789 IOMC

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Fig. 15. Video amplifier relative amplitude response with varying input frequency

and constant input voltage.

Fig. 16. Complete elec-

BOOTH WIRING

UTILITY BOXES MMINO MONITOR.

138

August 1952 Journal of the SMPTE Vol. 59

necessitating no unusual or complicated
wiring.

While it is expected that development
work will continue, the unit described
is a frozen design and is in production.
In conclusion, we have presented here-
with the present stage of commercial
availability of a simple, low-cost, instan-
taneous theater television projection
system.

Discussion

Robert E. Lewis (Armour Research Founda-
tion) : How many lumens do you get out
of the system?

Frank H. Riffle (Motiograph, Inc.) : (Mr.
Riffle read the paper.) The only actual
measurement that we have made is at the
corrector plate and it is about 160 foot-
candles.

Chauncey L. Greene (RKO Orpheum Theater,
Minneapolis): Perhaps I am again trying
to take in too much territory here, but I
would like to see if we can't translate those
figures somehow into a screen brightness.
Did I understand you that 160 foot-
candles of brightness, so to speak, of the
face of the tube.. .?

Mr. Riffle: No, that was at the correc-
tor plate.

Mr. Greene: Now, is there any way of
arriving at an approximate ratio between
that and the screen brightness for any
given picture size, that is, could we, for in-
stance, divide that area into the screen area
and apply a factor of loss?

Mr. Riffle: Yes — and in calculating
this, we find approximately 0.4 foot-candles
of light at the screen, which may appear to
be comparatively small; but the brightness
of the picture observed is entirely satis-
factory.

trical wiring diagram.

BOOTH WIRING

CONTROL BOX TO BE LOCATED NEAR POR* HOLE
FOR EASY MANIPULATION OF CONTROLS BJ
OBSERVATION.

NOTE

(21 5-PRONO SOCKETS a PLATE
SUPPLIED BY TRAD.

PROJECTOR WIRING

A.C. TO PROJECTOR "t

Trad and Muniz: Theater Television System

139

Theater Television Progress

By NATHAN L. HALPERN

This is a report on theater television developments in terms of the industry,
programs, program distribution and the public interest in this new medium.

N THE DEVELOPMENT of theater tele-
vision, as in all modern communications
media, the engineers have been the
pioneers. The records show that as long
ago as 1929, technical experiments in
large-screen television were being con-
ducted. Many engineers who have been
engaged in pioneering this new field,
will be interested in hearing of the prog-
ress that has been made along trails they
blazed.

There are four areas covered in this
report: (1) the industrial development of
theater television; (2) programs for
theater television; (3) the public's re-
action to these programs; and (4) the
distribution of programs to theaters.
Since future engineering developments
in this new medium are directly related
to the practical economics of theater tele-
vision, these areas are all important.

Today there are over 75 theaters in 37
cities from coast to coast with large-
screen television equipment. This is in
comparison to a single television-equipped
theater three short years ago. In
the past year alone, theater television has
increased its seating capacity 600%; the
number of cities with installations has
risen 300%. Notwithstanding these

Presented on April 21, 1952, at the Society's
Convention at Chicago, 111., by Nathan L.
Hal pern, Theatre Network Television, Inc.,
515 Madison Ave., New York 22, N.Y.

impressive figures, theater television is
only beginning to grow. There are 20,000
theaters to go.

Theater television installations will be
made eventually in all motion picture
theaters in the country. Although it is
off to a fast start, theater television has a
long way to go before it can fully realize
its great potentials. The harnessing of
this form of television by the motion
picture industry will offer the public a
new and different service. Theater tele-
vision will become a valuable national
resource dedicated to the entertainment
and education of the public.

Despite its early stage of growth, there
have already been over 300 individual
theater presentations of large-screen
television programs. While most of
these have been news and sports events,
there have been a few special entertain-
ment presentations, as well as special
government and industry uses of theater
television's closed circuits. With few
exceptions, the early presentations were
experiments, conducted to test public
reaction to, and the operation of, theater
television. They clearly demonstrated
that this new medium satisfied and pleased
its audiences. It has been, in fact, the
public's acceptance that has caused the
further development of theater television.

Theater television has already proved
that theater television programs can be

140

August 1952 Journal of the SMPTE Vol.59

successful. The conditions necessary for
successful special event presentations
have been emerging in the past year.
Exclusivity, proper promotion and some
regularity are all desirable, if not neces-
sary. Matinee sports presentations,
which bring new sports audiences into
theaters at unprecedented times, require
all three of these conditions to be favor-
able.

The most publicized theater television
programs to date were the series of prize
fights presented last summer. This series
of six fights, presented by Theatre Net-
work Television (TNT), was offered to a
public that was unacquainted with the
medium, and for this reason the series
was presented under adverse circum-
stances. The boxoffice results were
nothing short of startling. The overall
average attendance for all theaters on
all six TNT fights was 87% of capacity,
despite the fact that two of the fights
were not top attractions.

This boxoffice average is only a partial
indication of the great public interest in
these theater television programs. On
several of the fights, the numbers of
people turned away from boxoffices for
lack of seats were much larger than the
number of people packed into the theaters.
These turn-away crowds were only part
of the larger population that would
have attended, but for theater television's
limited capacity to accommodate the
public last summer.

Of importance, too, was the attraction
of part of the "lost audience" — non-
movie-goers — to the motion picture
houses. Theater television proponents
had, from the outset, maintained that
this new medium would attract new
audiences. New audiences added to
normal film audiences will expand theater
attendance in the years ahead.

It goes without saying that every
major medium must pass through an
investment period at the start, with op-
erating losses until it has grown suffi-
ciently. The pioneers in home television
broadcasting made large-scale invest-

ments and sustained high losses for years
of operation — losses that ran into
millions of dollars for single stations —
before they were in the black. The
significant thing about theater television
is that it has experienced profits on some
events from the outset. As compared
with television broadcasting, theater
television has required relatively small
investments and its operating losses have
been comparatively small. But before
examining the credit side of the ledger,
let's take a look at the debits.

The losses incurred in early theater
television have not been due to a lack of
appeal in its programs or in the medium
itself. These relatively small losses were
attributable to three factors: (1) the few
theaters sustaining the costs of big-time
attractions; (2) the pricing policies
followed by theatermen; and (3) the
absence of a regular, year-round flow of
programs and promotion.

Last summer, the TNT series of prize
fights was carried by an average of only
12 theaters. In spite of the very small
number of theaters which shared rela-
tively high unit costs, it was remarkable
how close to break-even these theaters
came on most programs. Profits were
made on individual fights. Naturally, a
larger number of theater installations
will reduce individual theater costs and
turn losses into profits. And the profits
will increase as the number of theater
television exhibitors grows.

A prime factor in the difference be-
tween profit and loss on theater television
events was the initial low admission price
policy of exhibitors. At the beginning of
the summer fight series, exhibitors were
literally giving their products away to
see whether people liked them. Some
exhibitors seemed to treat theater tele-
vision as a fight film, to be marketed as a
bonus to the feature movie. The cost of
theater television presentations added to
film exhibition meant exhibitors would
incur losses if regular movie admissions
were charged. Many chose this course
at the start, not realizing that the real

Nathan L. Halpern: Theater Television Progress

141

boxoffice pull was theater television, not
the movie attraction on such bills.
Theaters charged as little as 54^ net
admission for the first several theater
televised fights. There was no trouble
selling out on nights when film business
was ordinarily in the doldrums.

As theatermen saw the public demand
and satisfaction, they began to adjust
admission prices upward. Moreover,
exhibitors began to realize that a theater
television event was unique — entirely
different from a film which is shown con-
secutively, or even a live stage show that
is repeated throughout its run. A unique,
televised event - - valuable for the
moment — requires special handling and
pricing.

By the time of the Robinson-Turpin
bout, theaters had adjusted their admis-
sion prices to an average well over $2.00.
Every theater carrying the fight sold out,
evidencing the public's enthusiastic ac-
ceptance of this new entertainment
medium. The average theater television
gross was $5,000 per theater, with seating
capacities ranging from 1,100 to 4,000
seats. It became apparent that higher
prices for earlier theater television events
might have resulted in profits then, too.
Moreover, concession sales in theaters
boomed, increasing as much as 400%
above average.

I would like to give you an idea of
theater economics on a successful theater
television event at this early period.
Perhaps the best way to do this is by tak-
ing a specific example: the economics of
Theatre X, an actual theater, for one of
last summer's TNT fights. Theatre X
has 3,300 seats. With a $2.40 gross ad-
mission price, and a sellout with 473
standees crammed in, the net receipts,
after taxes, were $7,500. Total television
costs to the theater (relatively high be-
cause of so few theater installations)
were $4,000, leaving an operating tele-
vision profit of $3,500. The deduction of
normal house expenses and film distrib-
utor costs still left this exhibitor with a
whopping profit for a single theater tele-

vision show. His only regret was that he
had to turn away thousands of disap-
pointed people, for lack of room.

The economics of theater television
last summer on such individual events
clearly pointed up future prospects. If
this kind of operating profit could be
produced at the outset, with only a hand-
ful of theaters, the outlook for programs
carried by hundreds and then a thousand
or more theaters is fabulous.

The third factor affecting early theater
television — the absence of a regular,
year-round flow of programs — is due
in part to the newness of the medium.
The development of entertainment at-
tractions, to go along with outstanding
sports events, has preoccupied those of
us in theater television these past several
months. The entertainment desirable for
theater television must, of course, be
superior. Even now, theater television
is growing closer to the number of outlets
necessary to support regularly high-cost
presentations and talent.

In the developmental work put into
entertainment for theater television re-
cently, talent and craft unions were faced,
for the first time, with making decisions
on theater television. Most of these
unions have recognized the importance
of this new field and its gainful employ-
ment and compensation potentials for
their memberships, as well as its public
service aspects. Consequently, their at-
titudes are becoming progressively more
cooperative. Meanwhile, however, time
has been consumed in establishing a basis
for entertainment in theater television.

It is encouraging to report that there
is a wealth of superior talent and enter-
tainment eagerly awaiting the develop-
ment of theater television. There is no
lack of great entertainment, superior to
home television and different from mo vies,
for theater television programs. Once
the ground rules have been worked out,
TNT will launch a schedule of these great
programs.

Of paramount importance in limiting
the past presentation of theater television

142

August 1952 Journal of the SMPTE Vol. 59

programs has been the unavailability of
adequate AT&T facilities to network
theaters. The placement of theater
television installations necessarily has
been made along the routes of the coaxial
cable and microwave relay facilities of
AT&T. Most theaters in the country
cannot be serviced by present telephone
company facilities. This situation has
forced theater circuits to make multiple
installations in fewer cities, thus imped-
ing theater television's early growth.
Moreover, the lack of adequate AT&T
long lines to theaters located on the cable
and relay highways has impaired theater
television's ability to develop regular
program schedules.

Here is a concrete example of the
theater television distribution problem.
At the beginning of the year, TNT pro-
jected a series of nine programs, to be
presented between March 3 and April 1 3.
Considerable work went into the formu-
lation of this series, which included an
opera, a Broadway musical, a famous
Broadway stage show, a championship
fight, championship basketball tourna-
ments, and other sports events. TNT
requested AT&T clearances for each
program to installed theaters in 23 metro-
politan areas at the beginning of Febru-
ary, requiring replies in time for effectu-
ating the schedule.

The total number of long lines clear-
ances for cities requested by TNT of
AT&T for these programs was 207;
AT&T did not assure clearance of 151;
thus 73% of theater television's require-
ments were not fulfilled for the TNT
spring schedule.

The lack of AT&T long lines made this
program schedule impractical. Not all
theater television requests have met with
this fate. However, this experience
pointed up acutely that the telephone
situation has been a difficult road block
to the rapid growth of theater television,
and that AT&T has not added sufficient
distribution facilities for theater tele-
vision. The telephone companies have
shown increasing understanding of the

theater television facilities needs. As a
result, it is anticipated that AT&T will
free more facilities for theater television,
thereby speeding the growth of the me-
dium and increasing its own returns in
this field. In this direction, the de-
velopment of more reasonable telephone
charges for theater television should be
high on the agenda.

The FCC proceedings on theater tele-
vision channels will center attention on
practical alternatives to these facilities
problems. Although postponed in the
wake of the hectic activities surrounding
the lifting of the television freeze, it is
expected that the FCC will reschedule
the theater television hearings as soon as
possible. Meanwhile, theater television
must and will continue to move forward.

Problems on the road to the future are
being solved already. Every month the
number of theater television installations
increases, thus reducing the cost factors
for individual theaters. Currently, there
are a dozen theater television installa-
tions being made, including those of
United Paramount Theatres, Warner
Brothers Theatres and RKO Theatres.
Valuable experience in pricing has been
gained already. Programs are being
formulated by TNT for production. And
it is hopeful that intercity and intracity
telephone facilities will become increas-
ingly available at reasonable rates.

Theater television will add fine enter-
tainment of many kinds to its news and
sports events. It will provide valuable
services in the field of education, as well
as specialized closed circuit services to
government and industry. It is to be
hoped that the growth timetable will not
be prolonged by "faint heart" and "Let
George do it" attitudes in the industry.

The theater industry needs theater tele-
vision. The public has already shown
that it will go for it. Slowly simmering
during the past period, theater television
will erupt suddenly with its own formula
for success in show business. The road
may have obstacles but the future is
bright.

Nathan L. Halpern: Theater Television Progress

143

Proposed American Standard
16mm Motion Picture Projector
for Television

J. HE INITIAL WORK on this proposal was
done by an RMA Subcommittee,
TR4.4.2, and a first draft was circulated
in May 1950. Need for extensive re-
vision was indicated at the final meeting
of TR4.4.2 held in June 1 950. At about
this time, the present Joint RTMA/
SMPTE Committee on Television Film
Equipment was organized to replace the
RMA Subcommittee.

At the first meeting of the Television
Film Equipment Committee, the pro-
posal was again reviewed and revised
and a second draft incorporating the de-
sired changes was circulated in Septem-
ber 1950. The extensive nature of the
proposal precluded ready agreement,
and a third draft, February 1951, and a
fourth draft, May 1951, were required
before the committee could reach final
agreement. The latter was then sub-
mitted independently to the RTMA and
the SMPTE Standards Committee for
further action.

In the RTMA, the proposal TR4-4116
was accepted by TR4, approved for
circulation to industry by TREX and

released as Standard Proposal #365 in
June 1952.

In the SMPTE, the Standards Com-
mittee balloted on the question of
approving Journal publication of the
proposal for a 90-day period of trial and
comment and, with but a few exceptions,
voted affirmatively. The negative votes
were based on the objection that the
proposal was more of a procurement or
performance specffication than a stand-
ard defining required dimensional limits
for the purpose of aiding interchange-
ability. With the belief that publica-
tion would stimulate worth-while dis-
cussion, the Standards Committee gave
the necessary approval in June 1952.

Please send comments, in duplicate,
to Henry Kogel, Staff Engineer, before
December 15, 1952. If no adverse com-
ments are received during the three-
month trial period, the proposal will be
submitted directly to ASA Sectional
Committee PH22 with the recommenda-
tion that it be processed as an American
Standard.

144

August 1952 Journal of the SMPTE Vol.59

Proposed American Standard

16mm Motion Picture Projector

For Use With Monochrome Television Film

Chains Operating on Full-Storage Basis

(Fourth Draft)

PH22.91

1. Scope

1.1 This standard applies only to 16mm mo-
tion picture projectors in which the film is ad-
vanced intermittently.

1.2 Projectors complying with this standard
can be used only with film chains which oper-
ate on a full-storage basis.

1.2.1 In full-storage operation illumi-
nation from the projector is restricted to
the vertical retrace period of the tele-
vision scan.

1.3 Many of the characteristics of the pro-
jector cannot be standardized in specific terms
unless the pickup tube used in the film chain
is specified. Since the Type 1 850-A iconoscope
is used almost exclusively at present jn film-
chain equipment, it has been used as the basis
of standardization. If the projector is to be
used with any other type of pickup tube, it will
be necessary to modify the following para-
graphs of this Proposed Standard: 2.1, 2.2,
3.1, 3.2.1, 8.1 and all subparagraphs.

2. Image Dimensions

2.1 An image width of 4!/2 inches shall be
considered standard. (See Paragraph 1.3.)

2.2 The range of focus adjustment shall be
sufficient to accommodate widths of image
from 3% inches to 5 inches. (See Paragraph
1.3.)

2.2.1 The focusing operation shall not
displace the picture by more than 1.0%
of its width.

3. Projection Lens

3.1 Focal Length. In following sections, for
test purposes, the use of a lens having a focal
length of approximately 3]/2 inches will be
assumed. (See Paragraph 1.3.)

P. 1 of 8 pp.

3.2 Resolution.

3.2.1 Resolution shall be defined and
measured in accordance with American
Standard Z22.53-1946, except that
measurement shall be made with the
standard picture width. (See Paragraph
1.3.)

3.2.2 The resolution shall be at least
80 lines per millimeter for the patterns
identified as E and D and at least 90
lines per millimeter for all others.

4. Optical Axis

4.1 The projector shall include, or have
available as an accessory, a sturdy pedestal.
Means shall be provided to place the optical
axis (when level) at any required height from
47 to 49 inches from the floor.

4.2 A tilting mechanism shall be included
although this need not permit either quick
change or change during operation. The
range of tilt shall be sufficient to raise or lower
by 1 inch an image of standard width, pro-
jected by a 3]/2-inch lens.

4.3 A leveling mechanism capable of rotat-
ing the projector about an axis parallel to the
optical axis shall be included.

5. Film Gate

5.1 Dimensions. The dimensions of the pic-
ture aperture and its location relative to the
film shall be in accord with American Stand-
ard Z22.8-1950.

5.2 Lateral guiding. At the picture aperture
the sprocket hole edge of the film shall be
used for lateral guiding. (Note: This is an
exception to the recommendations of Ameri-
can Standard Z22.8-1950. For a discussion
of the problem involved, see Note 3 of Z22.8.)

NOT APPROVED

August 1952 Journal of the SMPTE Vol. 59

145

Proposed American Standard

16mm Motion Picture Projector

For Use With Monochrome Television Film

Chains Operating on Full-Storage Basis

(Fourth Draft)

PH22.91

6. Framing Device

6.1 The projector shall have a readily ac-
cessible means for positive framing of the pic-
ture when the projector is in operation. The
range of the framing mechanism shall extend
0.025 inches above and below the standard
position measured at the film. The framing de-
vice shall be free from creep during operation.

6.2 The method employed for framing shall
not change the position of the projected image
of the picture aperture by more than 1.0% of
the picture width over the full framing range.

7. Picture Stability

7.1 Definition.

7.1.1 The stability of the image de-
pends upon the ability of the projector
to locate succeeding frames of film in
exactly the same position relative to the
picture aperture. Failure to perform this
function perfectly results in either jump
(vertical instability) or weave (horizontal
instability) or both.

7.1.2 Jump and weave shall be meas-
ured in terms of the peak-to-peak ex-
cursions observed. In each case the
result shall be stated as a percentage
of picture width.

7.2 Standard.

7.2.1 Jump shall not exceed 0.2% of
picture width.

7.2.2 Weave shall not exceed 0.15%
of picture width.

7.3 Method of measurement.

7.3.1 Since jump and weave are
mechanical characteristics of the pro-
jector and are independent of image
magnification, it is recommended that
both be measured with the greatest
magnification that will still give a suffi-

P. 2 of 8 pp.

ciently bright image for direct observa-
tion.

7.3.2 Jump and weave are usually
measured by projecting a Steady Test
Film which has an extra perforation in
the center of the picture area. This test
perforation is made in the same opera-
tion in which the sprocket holes are
made and it is very precisely located
with respect to the sprocket holes. Film
of this type may be obtained from the
Society of Motion Picture and Television
Engineers.

8. Image Illumination

8.1 Intensity. There is no evidence to indi-
cate that any particular significance should
be attached either to the peak value of the
illumination or to the exact shape of the light
pulse as a function of time. Consequently, only
the time average value of illumination in-
tensity is standardized. However, in full-stor-
age operation the duration of the light pulse
will be approximately 5% of the period of a
television field. This short duty cycle is likely
to introduce large measurement errors unless
certain precautions are observed. (See Para-
graph 1.3.)

8.1.1 Definition. The intensity of illum-
ination will be measured in Iconoscope
Exposure Units (abbreviated IEU). The
IEU is analogous to the foot-candle. Just
as foot-candles are measured by a de-
tector having a spectral sensitivity simi-
lar to that of the human eye, so are lEU's
measured by a detector having a spec-
tral sensitivity similar to that of the Type
1850-A iconoscope. For illumination
from a blackbody radiator at a color
temperature of 2700 K, a foot-candle

NOT APPROVED

146

August 1952 Journal of the SMPTE Vol. 59

Proposed American Standard

16mm Motion Picture Projector

For Use With Monochrome Television Film

Chains Operating on Full-Storage Basis

(Fourth Draft)

PH22.91

meter and an IEU meter will give identi-
cal readings. (See Paragraph 1.3.)

8.1.2 Standard. The intensity of illumi-
nation shall be at least lEU'S.*
(See Paragraph 1 .3.)

8.1.3 Method of measurement.

8.1.3.1 The intensity of illumi-
nation shall be measured in the
plane of the standard image
with the detector in the central
area of the image. (See Para-
graph 1.3.)

8.1.3.2 The detector shall have
a spectral sensitivity matching as
closely as possible the spectral
sensitivity of the Type 1850-A
iconoscope. A sufficiently close
approximation is afforded by a
Weston Photronic Cell, Model
594RB, equipped with a Corning
filter, Type 5-51, 5562. (See
Paragraph 1.3.)

8.1.3.3 The meter used with
the Photronic Cell shall have a
resistance of 20 ohms or less.
Because the illumination pulse is
of short duration and high peak
intensity, the resistance of the
meter will cause errors in meas-
urement which increase rapidly
with resistance value. For a 20-
ohm movement, the error will
not exceed 2% over the antici-
pated range of intensities with
the Weston Model 594RB cell.
(See Paragraph 1.3.)

Field experience relating illumination in lEU's to
satisfactory quality is as yet quite limited. It has
not yet been possible to determine the number of
lEU's which represent the line of demarcation be-
tween satisfactory and unsatisfactory performance.

P. 3 of 8 pp.

8.1.3.4 The combination of
meter and cell shall be cali-
brated against a foot-candle
standard using a blackbody
source of illumination at 2700 K.
(See Paragraph 1.3.)
8.1.4 The source of illumination shall
be operated within any applicable rat-
ings established by the manufacturer of
the source.

8.2 Control of Intensity. It is probable that
means for varying the intensity of illumination
will be required for certain types of pickup
tube. However, present information is not suf-
ficent to permit the formulation of a standard.

8.3 Uniformity.

8.3.1 Intensity of illumination at any
point in the area of the standard image
shall be not less than 80% of the maxi-
mum intensity of illumination.

8.3.2 Upon replacement of an incan-
descent projection lamp, if such is used,
no readjustment shall be required to
achieve this distribution.

8.3.3 The receptive area of the light-
sensitive element used for these readings
shall have a diameter not greater than
5% of the picture width. No reading
shall be taken with the center of the re-
ceptive element closer to the edge of
the image area than 5% of the picture
width.

8.4 Color. Although color of illumination
may have significant effects on picture qual-
ity, present knowledge is not sufficient to per-
mit the formation of a standard.

8.5 Flicker. Variation from pulse to pulse of
the time integral of the illumination falling on
any small area of the image may, under some
conditions, give rise to visible flicker in the pic-

NOT APPROVED

August 1952 Journal of the SMPTE Vol. 59

147

Proposed American Standard

16mm Motion Picture Projector

For Use With Monochrome Television Film

Chains Operating on Full-Storage Basis

(Fourth Draft)

PH22.91

ture from the film chain. However, present
knowledge is not sufficient to permit the for-
mulation of a standard.
8.6 Illumination Period.

8.6.1 Definition.

8.6.1.1 The illumination period
is the interval of time in which
the instantaneous intensity of il-
lumination in any part of the
image area exceeds 10% of the
peak instantaneous intensity.

8.6.1.2 The length of the illum-
ination period shall be stated in
terms of a percentage of V,
where V is the time from the
start of one television field to the
start of the next field.

8.6.2 Standard. The illumination pe-
riod shall not exceed 5% of V. This
value is dictated by the presently ac-
cepted minimum value for the vertical
blanking period of the television system,
which is 5% of V.

8.6.3 Method of measurement. The il-
lumination period shall be measured by
means of a photocell, an amplifier, an
oscilloscope and a timing oscillator. The
photocell and amplifier must respond
without saturation to the peak intensity

encountered and the frequency response
of the combination shall be down not
more than 3 db at 50 kc.

9. Pull-Down Period

9.1 Definition. The pull-down period is the
interval of time in which film is moving through
the picture aperture.

9.2 Standard. The only restriction to be
placed on the pull-down period is that it shall

P. 4 of 8 pp.

never overlap any part of the illumination
period.

9.2.1 If, in a particular mechanism,
there is any possibility that the pull-
down period may vary in phase relative
to the illumination period, then the
mechanism shall be designed to allow
this phase to change by — 3% of V from
the optimum position with no overlap of
the two periods.

9.3 Method of measurement. The existence
of overlap may be detected by projecting a
test subject consisting of sharply defined white
objects on a black background, and inspect-
ing the projected picture for evidence of travel
ghost. For this test, film complying with the re-
quirements of American Standard Z22.54-
1946 is recommended, although many title
strips will be found quite satisfactory.

10. Phasing of Projector Relative to
TV Vertical Scan

10.1 For the case of a fixed relation be-
tween pull-down and illumination periods:

10.1.1 Means shall be provided for
setting the illumination period in any
desired phase relative to the 60-cycle
frequency which controls the phase of
the motor.

10.1.2 Each time the projector is
turned on, it shall re-establish this pre-
selected phase relation by fully auto-
matic means in less than 3 seconds.

10.1.3 During operation, the pre-
selected phase relation shall be main-
tained within ± '/2% of V.

10.2 For the case of the illumination period
locked to the vertical synchronizing signal and
independent of the pull-down period, means
shall be provided for insuring compliance with
Paragraph 9.2 of this Proposed Standard.

NOT APPROVED

148

August 1952 Journal of the SMPTE Vol. 59

Proposed American Standard

16mm Motion Picture Projector

For Use With Monochrome Television Film

Chains Operating on Full-Storage Basis

(Fourth Draft)

PH22.91

P. 5 of 8 pp.

11. Film Capacity and Reel Tension

11.1 The projector shall accommodate reels
of any capacity from 400 to 3600 feet which
comply with the requirements of Proposed
American Standard PH 22.1 1-1952.

1 1 .2 For any reel size in this range, the take-
up tension shall at no time be less than 3
ounces nor greater than 10 ounces (hub
diameters less than 4.5 inches excepted).

11.3 For any reel size in this range, the
braking mechanism on the feed reel shall not
cause a tension greater than 3 ounces (hub
diameters less than 4.5 inches excepted).

12. Film Life

12.1 After 100 passages through the projec-
tor mechanism, film shall exhibit no evidence
of damage either visible in the projected pic-
ture or audible in the reproduced sound sig-
nal.

12.2 In order that a loop of film may be
used in this test, renewal of the splice as many
times as may be necessary is permitted.

12.3 The film used in this test may and
should be carefully selected and lubricated.
The projector is not required to pass this test
with film which is in inferior condition.

12.4 Passage of a splice in good condition
through the mechanism shall not cause serious
disturbance, such as loss of loop, nor shall the
mechanism cause excessive damage to the
splice.

13. Starting Time

13.1 Definition. The interval between appli-
cations of power and the attainment of: (a)
synchronous operation of the motor and (b) a
flutter content in the sound output which is less
than the maximum specified in Paragraph
17.2.

13.2 Standard. The starting time shall not
exceed 5 seconds.

14. Film Speed

14.1 The nominal speed of projection shall
be 24 frames per second. This shall not be
interpreted as excluding the use of a 3-2
mechanism.

15. Stopping Distance

15.1 Definition. The length of film that
passes through the film gate after removal of
power.

15.2 Standard. The stopping distance shall
not exceed 3 feet.

16. Manual Drive

16.1 Some readily accessible means shall
be provided for slow-speed manual operation
of the mechanism as a check on threading, etc.

17. Sound) Scanning System

17.1 Synchronization. The film path dis-
tance measured in the direction of travel from
the center of the picture aperture to the point
to which sound scanning occurs shall be 26
frames — Vi frame.

1 7.2 Mechanical stabilization. The rms value
of the total (sum of all frequencies) flutter shall
not be greater than 0.25% when using a
3000-cycle flutter test film complying with vhe
requirements of American Standard Z22.43—
1946. Film splices shall not cause any serious
disturbance in sound stabilization.

17.3 Dimensions of Scanning Aperture. In
the plane of optimum focus the scanning light
beam shall have a maximum width of 0.0005
inches and a length of 0.071 ± 0.001 inches.
(Reference for length: American Standard
Z22.41-1946.)

NOT APPROVED

August 1952 Journal of the SMPTE Vol. 59

149

Proposed American Standard

16mm Motion Picture Projector

For Use With Monochrome Television Film

Chains Operating on Full-Storage Basis

(Fourth Draft)

PH22.91

17.4 Adjustment of Scanning Beam.

17.4.1 Lateral Adjustment. Means
shall be provided for adjusting the
lateral position of the scanning beam
such that the projector does not repro-
duce either signal on a buzz-track test
film complying with the requirements
of American Standard Z22.57-1947.

17.4.2 Azimuth Adjustment.

17.4.2.1 Means shall be pro-
vided for adjusting the azi-
muth of the scanning beam.

17.4.2.2 The azimuth shall
be adjusted to secure maxi-
mum response using a 7000-
cycle test film complying with
the requirements of American
Standard Z22.42-1946.

17.4.3 Focus Adjustment.

1 7.4.3.1 Means shall be pro-
vided for adjusting the focus
of the sound optics to place
the plane of optimum focus in
coincidence with the emulsion
plane.

17.4.3.2 Focus shall bead-
justed to secure maximum re-
sponse using a test film com-
plying with the requirements of
American Standard Z22.42-
1946.

1 7.4.3.3 Means shall be pro-
vided for rapidly and accu-
rately shifting the plane of
optimum focus to coincide with
the emulsion position on either
side of the film.

1 7.5 Light Distribution. The light distribution
in the scanning aperture shall be sufficiently
uniform to produce a signal across a resistive

P. 6 of S pp.

load at the output of the preamplifier which is
constant within ± 1.5 db when reproducing a
Scanning Beam Uniformity Test Film comply-
ing with the requirements of American Stand-
ard Z22.80-1950 or Z22.81-1950.
17.6 Exciter Lamp.

17.6.1 The exciter lamp shall be so
mounted as to permit rapid replace-
ment.

17.6.2 It is not desirable that uni-
formity of illumination in the scanning
aperture be critically dependent upon
exciter lamp position. If this condition
exists, means shall be provided for in-
dependent horizontal and vertical ad-
justment of the exciter lamp position.

17.6.3 The exciter lamp shall be a
prefocused type unless the lamp holder
is a replaceable type equipped with
adequate adjustments which can be
preset, and a spare lamp holder is pro-
vided.

1 7.6.4 The exciter lamp shall be op-
erated at all times within any appli-
cable ratings established by the manu-
facturer of the lamp.

18. Sound Amplification System

Any statement of sound-reproduction charac-
teristics must necessarily cover the perform-
ance of a preamplifier which is specifically
designed as a component of the projector.
However, it is not essential that all or even any
part of the preamplifier be included in the pro-
jector structure. Wherever they are mounted,
all parts of the preamplifier should be readily
accessible.

18.1 Output Impedance. There shall be
available output impedances of 600 and 150
ohms, both to be balanced outputs.

NOT APPROVED

150

August 1952 Journal of the SMPTE Vol. 59

Proposed American Standard

16mm Motion Picture Projector

For Use With Monochrome Television Film

Chains Operating on Full-Storage Basis

(Fourth Draft)

PH22.91

1 8.2 Output Level.

18.2.1 Standard. The output level
shall be -lOdbm.

1 8.2.2 Method of measurement. This
level shall be produced using level test
film complying with the requirements
of American Standard Z22.45-1946.

18.2.3 A gain normalization control
shall be provided having sufficient
range to insure compliance with the
above standard for any normal com-
bination of exciter lamp, photocell and
amplifier tubes.

18.3 Frequency Response.

1 8.3.1 If the frequency response from
film to output is fixed, it shall be flat
within ± 1 db from 50 to 6000 cycles
per second. If tone controls are pro-
vided in the preamplifier, their range
of adjustment shall include this re-
sponse.

18.3.2 Method of measurement. The
frequency response shall be determined
by means of a multifrequency test film
complying with American Standard
Z22.44-1946. The amplitude of re-
sponse shall be measured across a re-
sistance load at the output of the pre-
amplifier. The frequency response shall
be determined with standard gain.
(See Paragraph 18.2.)

18.4 Distortion. Although it is desirable to
state a distortion standard which will cover
the photocell as well as the preamplifier, a
method of measurement which will accomplish
this result is not known. Consequently, the
present Standard Proposal covers only distor-
tion in the preamplifier.

1 8.4.1 Standard. Total harmonic dis-
tortion in the preamplifier at standard
output level shall not exceed !/2% in
the range from 50 to 6000 cycles per
second.

1 8.4.2 Method of Measurement. Test
signals from an oscillator shall be ap-
plied at the photocell input of the pre-
amplifier and distortion shall be meas-
ured with a distortion analyzer at the
preamplifier output at standard output
level.

1 8.5 Preamplifier Noise Level.

18.5.1 Standard. The noise level of
the preamplifier shall be —65 dbm.

1 8.5.2 Method of measurement. The
noise level of the preamplifier shall be
measured at standard gain (see Para-
graph 18.2), with the projector run-
ning, the exciter lamp energized and
no light entering the photocell.

18.6 Overall Noise Level.

18.6.1 Standard. The overall noise
level shall be -55 dbm.

1 8.6.2 Method of Measurement. The
overall noise level shall be measured at
standard gain (see Paragraph 18.2),
with the projector running, the exciter
lamp energized and'no film in the ma-
chine.

Appendix A

The gate of the projector should be designed
to provide easy access to aperture and rails
for thorough and effective cleaning and in-
spection.

NOT APPROVED

August 1952 Journal of the SMPTE Vol. 59

151

Proposed American Standard

16mm Motion Picture Projector

For Use With Monochrome Television Film

Chains Operating on Full-Storage Basis

(Fourth Draft)

PH22.91

P. • of 8 pp.

Appendix B

The American Standards listed below have
been cited in the present Proposed Standard.
Copies of any of the reference standards may
be obtained from the American Standards
Association, 70 East 45 Street, New York 17,
New York.

1. Z22.8-1950

Location and Size of Picture Aperture
of 16mm Motion Picture Projectors.

2. PH22.11-1952

16mm Motion Picture Projection Reels.

3. PH22.16

Emulsion and Sound Record Positions
in Projector for Direct Front Projection
of 16mm Sound Motion Picture Film.

4. Z22.41-1946

Sound Records and Scanning Area of
16mm Sound Motion Picture Prints.

5. 222.42-1946

Sound-Focusing Test Films for 16mm
Sound Motion Picture Projection Equip-
ment.

6. Z22.43-1946

3000-Cycle Flutter Test Film for 1 6mm
Sound Motion Picture Projectors.

7. Z22.44-1946

Multi-Frequency Test Film for Field
Testing 16mm Sound Motion Picture
Projection Equipment.

8. Z22.45-1946

400-Cycle Signal Level Test Film for
16mm Sound Motion Picture Projection
Equipment.

9. Z22.53-1946

Method of Determining Resolving
Power of 16mm Motion Picture Projec-
tion Lenses.

10. Z22.54-1946

Freedom from Travel Ghost in 16mm
Motion Picture Sound Reproducers.

11. Z22.57-1947

Buzz-Track Test Film for 16mm Motion
Picture Sound Reproducers.

12. Z22.80-1950

Scanning-Beam Uniformity Test Film
for 16mm Motion Picture Sound Repro-
ducers (Laboratory Type).

13. Z22.81-1950

Scanning-Beam Uniformity Test Film
for 16mm Motion Picture Sound Re-
producers (Service Type).

NOT APPROVED

152

August 1952 Journal of the SMPTE Vol. 59

Proposed Amendments to the Bylaws

TWO SUGGESTED AMENDMENTS to the Bylaws

of the Society are presented here, with the
Board of Governors' reasons for proposing
that they be adopted. They represent the
first formal result of an official study of
organization and operating practices of
SMPTE started last January at the Board's
request and are intended to state clearly
two matters of importance. The first re-
cites the long established policy of the
Society respecting the voluntary nature of
Standards and Recommendations de-
veloped within SMPTE engineering com-
mittees. The second sets down, of legal
necessity, a newly drawn provision for dis-
position of the Society's assets in the un-
likely event of dissolution.

For these amendments to become official
they must be processed as outlined in By-
law XIII last published on page 348 of the
Journal for April this year. The Board of
Governors initiated the recommendation
during its meeting in New York on July 17.
Publication here is also required and next
comes consideration by the voting members
during the regular meeting of the Society
which is held annually during the fall con-
vention. This year it will occur at 3 P.M.
Monday afternoon, October 6, just pre-
ceding the first technical session of the
Society's 72d Convention at the Hotel
Statler in Washington, D.G.

Voluntary Standards

As a part of his regular quarterly report
to the Board of Governors, Fred T. Bow-
ditch, Engineering Vice-President, stated
his belief that although the members of the
Society knew that American Standards for
which the Society serves as sponsor, and
other formal Recommendations published
by the Society, were voluntary, and that
their existence did not preclude members or
nonmembers from manufacturing and sell-
ing products not conforming to the Stand-
ards, it would be advisable to incorporate a
provision to that effect in the Bylaws of the

Society. The Board was in agreement and
passed a Resolution proposing adoption of
the following:

BYLAW XIV

Standards and Recommendations

Sec. 1. American Standards sponsored
by the Society and the Society's Recom-
mendations are proposed and adopted in
the public interest and are designed to
eliminate misunderstanding between the
manufacturer and the purchaser and to
assist the purchaser in selecting and ob-
taining the proper product for its particular
need. Existence of such a Standard or
Recommendation does not in any respect
preclude any member or nonmember from
manufacturing or selling products not con-
forming to the Standard or Recommenda-
tion.

Disposition of Assets

Herbert Barnett, Executive Vice-Presi-
dent, who served as Chairman in the ab-
sence of President Peter Mole, stated that in
his opinion it would be advisable to provide
in the Bylaws for disposition of the Society's
assets in case of dissolution. After ex-
tended discussion, the Board voted in favor
of such a provision, approving unanimously
the following proposed amendment :

BYLAW XV

Disposition of Assets and Dissolution

Sec. 1. Upon the dissolution of the
Society and after payment of all indebted-
ness of the Society, the funds, investments
and other assets of the Society shall be
given and transferred to some other non-
profit organization having objects similar
to those of the Society. The selection of
such other organization shall be made by
the Board of Governors either at a regular
meeting of said Board of Governors or at a
special meeting of said Board called for the
purpose of selecting such an organization.

August 1952 Journal of the SMPTE Vol. 59

153

72d Semiannual Convention

This Fall's Convention at the Hotel Statler, Washington, D.C., October 6-10, will be
a blaze of highlights with very strong base lighting of the fields of Society interest, for de-
spite the heat, humidity, politics and other summer distractions all the plans keep building .

Program Chairman Joe Aiken has lined up the scores of papers into some 14 sessions
to release the Advance Notice of the Convention to be mailed to all members in the
Western Hemisphere on August 6. This carries the tear-off postal for reserving hotel
rooms. If you have not made reservations and need a copy of the postal for convenience,
ask Society headquarters for one. The Advance Notice also has the abstract of the
technical papers sessions.

Although the sessions are all arranged, occasionally authors have to withdraw a paper —
so if you have a special paper suddenly cleared, it might still be fitted into the Final Pro-
gram. If so, write air mail or wire: Joseph E. Aiken, 116 N. Galveston St., Arlington,
Va.

One large and special part of the technical program will be the first International Sym-
posium on High-Speed Photography which is planned as fully the equivalent of two days
of sessions, some of them concurrent with sessions on topics from other parts of the Soci-
ety's interest. John H. Waddel is Chairman for this symposium.

16mm equipment maintenance is the subject of another session being developed by
R. T. Van Niman who will welcome all who come bearing manuscripts, ideas or possibly
other contributions to this symposium and discussion.

A session on magnetic striping has been organized by Glenn Dimmick. This session
contains four formal papers but there is still allowable room for anyone who feels that he
can or should make a contribution to this subject.

Highlights that can now be mentioned are : descriptions of recording television pic-
tures on magnetic tape presentation of the Signal Corps' Mobile Television System;
report on the National Television Systems Committee accomplishments in color television;
laboratory session papers on high-speed processing, rapid drying, and butt-weld splicing.

Bill Kunzmann, the Society's Convention Vice-President, gave the Board of Governors
a complete report in July, covering all the arrangements and commitments made for the
Washington convention. Bill was in Washington in late May and at that time held an
organizational meeting which resulted in our having the following roster of folks who will
put over the operation of the convention :

Program Chairman — Joseph E. Aiken

International Symposium on High-Speed Photography — John H. Waddell

Papers Committee — Chairman, Edward S. Seeley — Vice-Chairmen, Joseph E. Aiken,
Fred G. Albin, Geo. W. Colburn, Gerald G. Graham, W. H. Rivers and John H.
Waddell

Local Arrangements — Joseph E. Aiken

Hotel Reservations and Transportation — Henry Fisher

Luncheon and Banquet — Nathan D. Golden

Membership and Subscriptions — Ray Gallo, assisted by G. J. Badgley

Motion Pictures — James Frank, Jr., assisted by John V. Waller

Naval Ordnance Laboratory Session Arrangements — Max Beard

Projection, 35mm and 16mm — Carl R. Markwith and Henry F. Heidegger, assisted by
John V. Waller, and members Local 224, I.A.T.S.E.

Public Address and Recording — J. Clinton Greenfield

Publicity — Harold Desfor, assisted by Leonard Bidwell and J. A. Moses

Registration and Information — Keith B. Lewis, assisted by P. M. Cowett, Fred W. Gar-
retson, Max Kerr, J. A. Moses and Howland Pike

Television — Col. C. S. Stodter, R. N. Harmon and W. P. Button

Ladies Reception and Registration — Mrs. N. D. Golden and Mrs. J. E. Aiken, Co-
hostesses

154

Engineering Activities

Development of American Standards

Motion picture — and related tele-
vision — standards in the United States are
today developed primarily by SMPTE En-
gineering Committees. While that is wide-
spread knowledge, the steps in that develop-
ment are probably not so well known. A
brief review of the procedures used in produc-
ing American Standards in cinematography
is therefore given below. It is hoped that an
awareness of these procedures will make for
an even wider participation in standards
activity, which can only serve to improve
the quality and observance of these stand-
ards.

1. Request for Standard: The need for
a standard may be brought to the attention
of the Society's Engineering Vice-President
by anyone interested: manufacturer, con-
sumer, Society member, government body,
etc.

2. Drafting the Standard: The Engi-
neering Vice-President estimates the gen-
eral value of the request and refers the
project to the appropriate Engineering
Committee. The Committee, a broad
representative group of some phase of the
motion picture industry, makes any re-
quired studies or surveys and prepares a
draft standard.

3. Reviewing the Standard: After the
Engineering Committee approves its
"final" draft, the proposed standard goes
through an extensive review to assure the
kind of acceptance required under our
system of voluntary standards.

a. Standards Committee: The SMPTE
Standards Committee is composed, in the
main, of the chairmen of the engineering
committees. This first review of the pro-
posal is therefore designed to achieve agree-
ment within the Society. Approval by the
Standards Committee is required before the
draft can be published in the Journal.

b. Journal Publication: Publication of the
draft for some stated period (usually 3
months) for trial and comment provides all
Journal readers an opportunity to study and
criticize the proposal.

c. ASA Sectional Committee, PH22: If no
adverse comments have been received dur-
ing the trial period, the Engineering Vice-
President transmits the proposed standard

to PH22 with a recommendation that it be
processed as an American Standard.
PH22 is composed of representatives from
every group having a vital interest in cine-
matographic standards. Approval by
PH22 generally indicates that the technical
content of the standard is in good order.

d. SMPTE Board of Governors: After
approval, PH22 returns the standard to the
Society for sponsor approval which is con-
ferred by Board of Governors action.

e. Photographic Standards Correlating Com-
mittee: At this point and on behalf of the
Board of Governors, the Executive Secre-
tary formally transmits the proposed
standard to the Director of the ASA, con-
cluding Society action on that particular
standard. The Correlating Committee is
an ASA body formed to integrate the
standards activity of all elements of the
photographic industry and so reviews all
photographic standards proposals before
final approval is granted.

4. American Standard: A proposed
standard acquires the stamp "American
Standard" upon approval of the ASA
Standards Council, the final board of re-
view. This group has representatives from
each ASA Member Body and thus provides
a clearing house for vast numbers of stand-
ards from widely diversified industries.
Publication in the SMPTE Journal com-
pletes the lengthy journey from request to
American Standard.

It should be noted that any group may
submit a proposed standard to PH22 for
processing as an American Standard and
this the Motion Picture Research Council
has done in quite a few instances. This in
no way changes the ensuing procedure
since the SMPTE as sponsor of PH22 must
review the proposal in order to authorize
the required sponsor approval.

Your attention is also drawn to the fact
that the technical committees of the
Society are not closed corporations. A
request to have your organization repre-
sented on one or several engineering com-
mittees would be welcomed by the Engi-
neering Vice-President and would receive
serious consideration — Henry Kogel, Staff
Engineer.

155

Canadian Standards Association

The Canadian Standards Association was
established by Dominion charter granted
in 1919. As a result of experience gained
during several years of operation and
particularly during the war years the
charter was amended in 1944 to embrace
a broader field of operation as outlined
below:

(a) To provide, originate and furnish
Canadian standards of any nature what-
soever which are in the interests of pro-
ducers and users; to coordinate the efforts
of producers and users toward the improve-
ment and standardization of materials,
processes and related matters; to provide
systematic means by which organizations
interested in standardization work may
cooperate in establishing and promoting
Canadian standards to the end that
duplication of work and the promulgation
of conflicting standards may be avoided.

(b) To serve as a clearing house for
information on standardization work in
Canada and foreign countries; to further
the standardization movement as a means
of advancing the national economy, and to
promote a knowledge of, and the use of,
approved Canadian standards both in
Canada and foreign countries; to act as
an authoritative Canadian channel in
international cooperation in standardiza-
tion work.

(c) To register in the name of the
Association, and to hold, own, use and
operate any and all trade marks, proof,
letter or device and to enforce and protect
the use of such marks, proofs, letters or
devices and to oppose any proceedings or
applications which may seem calculated
directly or indirectly to prejudice the
interests of the Association.

Committee Organization

The Canadian Standards Association
has close contact, by direct representation,
with the following classifications of interest :
Manufacturers, Departments of the Do-
minion Government, Provincial Govern-
ments, Public Utilities, Educational Insti-
tutions, Professional Bodies, Labour Or-
ganizations, Purchasing Departments, In-
surance Interests.

From the various classifications of in-
terest a series of Divisions has been estab-

lished covering such representative fields
as Textiles, Agriculture, Pulp and Paper,
Steel Construction, Electrical Engineering,
etc. From these Divisions a Main Com-
mittee is drawn, each member serving for
a period of three years and eligible for
further service at the discretion of the
nominating interests. This is the govern-
ing body of the C.S.A.

From the Main Committee, members
are elected by the Divisions to form the
Executive Committee which is the ad-
ministrative body of the Association.

Sectional committees are appointed by
the Divisions, each sectional committee
consisting of from 10 to 30 members,
representing the best available knowledge
and experience in their respective fields.
Their responsibility is to supervise the
work of standardization with the scope of
each division. They are responsible for
the approval of specifications, which have
been developed by their working com-
mittees and for submitting same to the
Executive Committee for final approval
and publication.

When a request is received to produce
a standard specification for any commodity,
it is referred to the division interested,
for consideration and recommendation to
the Executive Committee for action.
Should there appear to be a reasonable
demand for the standard in question and
sufficient information available to assure
satisfactory completion of the work,
authority will be given to the division by
the Executive Committee to proceed with
the preparation of a standard.

If sufficient information appears to be
lacking, and scientific investigation is
considered necessary, proposals will be
made to a recognized research body,
such as the National Research Council,
to conduct tests or make investigations
in order to provide needed information
that will permit an authoritative standard
to be prepared.

These Working Committees consist of j
a variable number of members ranging i
from five or six to as high as thirty or more, j
depending on the nature of the work to be
done.

As work progresses, a draft specification
is prepared and subsequently discussed

156

at meetings of the Working Committee.
Verbal recommendations for revision,
and those received from members unable
to attend or interests not desiring direct
representation, receive full consideration.
This usually necessitates the preparation
of several draft specifications, requiring
considerable time before a proposed stand-
ard is considered ready for publication.

Every effort is made, not only to assure
full representation of the views of all
interests, but to tap every available source
of information, both foreign and domestic.
Accordingly, when a standard is published,
it represents, as far as possible, the best
available authority consistent with general
knowledge and local conditions.

Approvals Division

The G.S.A. has had a certification pro-
cedure in effect for many years and the
C.S.A. label is recognized throughout
Canada as a symbol of assurance that
electrical equipment and devices are
reasonably free from fire and accident
hazards. This Approval Service, which
now insures compliance with safety and
performance standards can be extended,
as and when industry becomes convinced
that certification, on a quality basis, is
beneficial to the producer as well as to the
consumer. The details of the procedure
will be developed in collaboration with
appropriate producer and consumer in-
terests as required.

C.S.A. Standards

An important feature of G.S.A. stand-
ards, in line with British and American
standardizing practice, is that they are
"voluntary" standards. As such, they
serve as recommendations to industry
and may or may not be adhered to by the
manufacturers concerned.

Such standards may, on the other hand,
become mandatory by adoption by a
government department having legal au-
thority to enforce their requirements in
the matters of governmental purchases,
when the standards concern specific ma-
terials or products. The Association has
published approximately 200 such stand-
ards— thus far limited to the various
sections of engineering.

Photography

The G.S.A. Sectional Committee on
Photography was organized in 1948 with

Dr. L. E. Howlett of the National Re-
search Council as chairman. Three speci-
fication committees are at work in this
field at the present time:

Z7.1 — Motion Picture Photography;
Z7.2 — Still Photography; and
Z7.3 — Survey Photography.
Committee Z7.1 has completed a review
of all basic A.S.A. and B.S.I, motion pic-
ture standards and some 43 have been
published by the C.S.A. A specification
for an industrial and educational model
16mm projector is now in the final draft
stage. Members of this committee with
their affiliations are:
A. H. Simmons (Secretary), Gevaert

(Canada) Limited, Ottawa
Harold Walker, Dominion Sound Equip-
ments Limited, Montreal
Don Spring, Canadian Kodak Sales Ltd.,

Toronto
John Gerald, Ansco of Canada Ltd.,

Toronto
Sqn. Ldr. N. Drolet, Armed Services,

Ottawa
Gordon Adamson, National Film Society,

Ottawa
Gaudry DeLisle, Department of Education,

Quebec City

H. Goldin, Consulting Engineer, Toronto
M. Metzger, Associated Screen News Ltd.,

Montreal
Arthur Elsey, Canadian Industries Ltd.,

Montreal
P. D. Carmen, National Research Council,

Ottawa
A. J. Pauley, The Odeon Theatres

(Canada) Ltd., Toronto

F. T. Myles, R.C.A. Victor Co. Ltd.,

Montreal
John Young, Benograph, Montreal

G. Graham (Chairman), National Film
Board, Ottawa

Editor's Note: This report was kindly
prepared by Gerry Graham, Director of
Technical Operations, National Film Board
of Canada, upon our request for help in
adding to the series of brief articles de-
scribing organizations which SMPTE
members wish to know more about.
Previous stories have been about the
American Documentation Institute, the
Biological Photographic Association, and
the University Film Producers Association.
Your suggestions for subjects or possible
contributors for other articles are welcome.

157

New Members

The following members have been added to the Society's rolls since those last published.
The designations of grades are the same as those used in the 1952 MEMBERSHIP DIRECTORY.

Honorary (H)

Fellow (F)

Active (M)

Associate (A)

Student (S)

Baggs, Sgt. David A., Officer in Charge of
Motion Picture Processing, U.S. Air
Force. Mail: 2413 Girard PL, N.E.,
Washington 18, D.G. (A)

Barr, William J., Camera Technician,
Warner Bros. Mail: 5537 Costello
Ave., Van Nuys, Calif. (A)

Benedict, Joel A., Director, Bureau of
Audio-Visual Aids, Arizona State Col-
lege. Mail: 929 McAllister, Tempe,
Ariz. (M)

Beyer, Walter, Motion Picture Engineer,
Bell & Howell Co. Mail: 7455 N.
Greenview Ave., Chicago 26, 111. (A)

Board, Cornelius Z., Arizona State Col-
lege. Mail: Route 1, Scottsdale, Ariz.
(S)

Bonner, Ray S., Recording Engineer,
Gallagher Films, Inc. Mail: 5062 N.
54 St., Milwaukee, Wis. (A)

Cackowski, John, University of California.
Mail: 5324 Monroe St., Los Angeles
38, Calif. (S)

Chaffee, William H., President. Model
Builders, Inc., 5300 W. 63 St., Chicago
38, 111. (.M)

Clark, Dick H., Student and Teaching
Assistant, University of California, Mo-
tion Picture Dept., 405 Hilgard, Los
Angeles, Calif. (A)

Cooper, Richard J. G., Technical Officer,
Dept. of National Defense, No. 11 Supply
Depot, R.C.A.F., Calgary, * Alberta,
Canada. (A)

Copeman, Robert A., Motion Picture
Service Engineer, Box 2140, Salisbury,
Southern Rhodesia. (A)

Curran, Charles W., Motion Picture Pro-
ducer, Times Square Productions, Inc.
Mail: 145 W. 45 St., New York 36,
N.Y. (M)

Damm, Roger, American Television Insti-
tute. Mail: 7408 Warren Ave., Forest
Park, 111. (S)

Donovan, Lewis N., Chief Radio Oper-
ator, Alberta Government, Dept. of
Lands & Forests. Mail: 10028—105
St., Edmonton, Alberta, Canada. (A)

Dunn, Reginald S., Laboratory Tech-
nician, Color Reproduction Co. Mail:
4841 Stansbury Ave., Sherman Oaks,
Calif. (A)

Edwards, Marvin J., Arizona State Col-
lege. Mail: 6225 N. 47 Ave., Glen-
dale, Ariz. (S)

Fernandez, Victor M., National Airlines,

Inc. Mail: 13 y Ave. Primera, Ampl.

de Almendares, Havana, Cuba. (A)
Gerard, Morton T., Jr., Motion Picture

Photographer, North American Avia-
tion, Inc. Mail: 2457 Ashland Ave.,

Santa Monica, Calif. (A)
Gilkeson, David C., Project Engineer

(Optics), Wollensak Optical Co., 850

Hudson Ave., Rochester 21, N.Y. (M)
Hall, Carlisle D., Laboratory Manager,

Ansco. Mail: 5506 N. Winthrop Ave.,

Chicago 40, 111. (M)
Herzig, Leonard A., President, Sound

Engineer, Prestoseal Manufacturing

Corp. Mail: 87-11— 35 Ave., Jackson

Heights, N.Y. (M)
Hine, Sheldon, Technical and Engineering

Photography, 2538 Joan St., Fort

Wayne, Ind. (A)
Holblinger, Anton, Sound Engineer,

Photo-Magnetic Sound Studio, Inc.

Mail: 35 Princeton St., Valley Stream,

L.I., N.Y. (M)
Jennings, Forrest, Laboratory Technician,

Color Reproduction Co. Mail: 2363

Hermits Glen, Hollywood 46, Calif.

(A)

Johnson, Culver, Engineer, Culver John-
son Research, 871 Seventh Ave., New

York, N.Y. (M)
Jones, Almon, U.S. Naval Photographic

Center. Mail: 3130 Knox St., S.E.,

Washington, D.C. (A)
Klein, Gerard, New York University.

Mail: 205 Beach 81 St., Rockaway

Beach, N.Y. (S)
Marcus, Wil, Motion Picture Producer,

Loucks & Norling Studios, 245 W. 55 St.,

New York 19, N.Y. (M)
Meunier, Jean L., President, Institut

Teccart, Inc., 3155 Hochelaga St.,

Montreal 4, Canada. (A)
Mikrut, Stanley M., Motion Picture Lab-
oratory Technician, Coronet Films.

Mail: 2460 Winona St., Chicago 25,

111. (A)
Minis, Charles W., Mechanical Engineer, j

Technicolor Motion Picture Corp.

Mail: 124^ N. Parkview St., Los!

Angeles 26, Calif. (A)
Reiche, Ludwig P., Electrical Engineer, j

International Telemeter Corp. Mail:

1445 Miller Way, Hollywood 46, Calif.

(M)

158

Rocha, Gustavo Humberto E., Head, tion, RCA Broadcast Section. Mail:

Sound Service and Installation Dept., 222 W. Plumstead Ave., Lansdowne, Pa.

Casa Ehlers. Mail: Abraham Gon- (M)

zalez #4, Mexico- City, Mexico. (A) Vaughan, Leslie D., Photographer, State

Scherlis, William, Cameraman, 241 U. S. Geological Survey, 404 Natural Re-
Grant Hotel, San Diego 15, Calif. (A) sources Bldg., Urbana, 111. (A)

Schulman, Marvin, Television Engineer, Wallace, Charles A., Arizona State Col-

KPIX, Inc. Mail: 175 Buckingham lege. Mail: 600 E. Second, Roswell,

Way, Apt. 1A, San Francisco 27, Calif. N.M. (S)

(A) Winkler, Ben, Sound Mixer, Radio

Simpson, Richard L., Motion Picture Corporation of America. Mail: 11209

Projection Equipment Mechanic, Naval Emlita St., North Hollywood, Calif.

Photographic Center. Mail: 3716 (A)

Second St., S.E., Washington 20, D.C. Wolfe, Benjamin, Television Broadcast

(A) Engineer, WAAM-TV. Mail: 3513

Steel, Lt. Col. W. Arthur, Radio Engineer, Lucille Ave., Baltimore 15, Md. (A)
Federal Electric Manufacturing Co. Worley, E. Max, Motion Picture Tech-
Mail: 4737 Grosvenor Ave., Montreal, nician, Color Reproduction Co. Mail:
P.Q., Canada. (M) 10552 Putney Rd., Los Angeles 64, Calif.

Theiss, Sylvester E., Technical Writer (A)
(Electronics), U.S. Government. Mail:

310 Audrey La., S.E., Washington 20, CHANGES IN GRADE

D.C. (M) Miller, William J., (A) to (M)

Tunnell, George W., Product Administra- Roberts, Paul M., (S) to (A)

SMPTE Lapel Pins

The Society will have available for mailing after September 15, 1952, its gold and blue
enamel lapel pin, with a screw back. The pin is a £-in. reproduction of the Society

symbol — the film, sprocket and television tube — which appears on the Journal cover.

The price of the pin is $4.00, including Federal Tax; in New York City, add 3%
sales tax.

Meetings

72d Semiannual Convention of the SMPTE, Oct. 6-10, Hotel Statler,

Washington, D. C.

Other Societies

International Society of Photogrammetry, Conference, Sept. 4-13, Hotel Shoreham,

Washington, D.C.

American Standards Association, Third National Standardization Conference, Sept.

8-10, Museum of Science and Industry, Chicago, 111.

Illuminating Engineering Society, National Technical Conference, Sept. 8-12, Edge-
water Beach Hotel, Chicago, 111.

Biological Photographic Association, Annual Meeting, Sept. 10-12, Hotel New Yorker,

New York

National Electronics Conference, Annual Meeting, Sept. 29-Oct. 1, Sherman Hotel,

Chicago, 111.

Optical Society of America, Oct. 9-11, Hotel Statler, Boston, Mass.

American Institute of Electrical Engineers, Fall General Meeting, Oct. 13-17, New

Orleans, La.
American Standards Association, Annual Meeting, Nov. 19, Waldorf-Astoria, New York

SMPTE Officers and Committees: The roster of Society Officers and the
Committee Chairmen and Members were published in the April Journal.

159

New Products

This 5000-w Featherlite, weighing only
21 Ib, is among the spotlights and other
new studio lighting equipment described
in a brochure by Century Lighting, Inc.,
521 W. 43d St., New York 36, N.Y.
Other equipment is: aluminum barn
doors, mechanical dimmers, light lifts,
hangers and mike boom.

The Hy-Arc is a new carbon-arc pro-
jection lamp for indoor and medium-size
drive-in theaters that has been announced
by the Theatre Equipment Section, RCA
Victor Division of Radio Corporation of
America, Camden, NJ. Features of the
lamp are : a system of magnetic stabiliza-

tion of the arc flame; water-cooled, non-
rotating positive carbon; and a 15-in.
high-speed reflector. The lamp's output
is approximately 18,000 1m. It operates
with a 9-mm X 20-in. high-intensity
positive carbon and a ^-in. X 9-in.
negative carbon at currents from 70 to
90 amp.

160

SMPTE Engineering Activities

A report by F. T. BOWDITCH, Engineering Vice-President

_L HE ENGINEERING ACTIVITIES of the

Society of Motion Picture and Tele-
vision Engineers are much more ex-
tensive than perhaps most members
realize. Engineering Committee reports
appear in the Journal from time to time,
but usually these give a detailed picture
in a rather limited field rather than a
broad view of the total activity. The
frequent publication of proposed Ameri-
can Standards is another evidence of
Society engineering activity, but this
has sometimes created the feeling that
the preparation of Standards proposals
is the only activity in which the Engi-
neering Committees of the Society are
engaged. For these reasons, the writer
has been encouraged to prepare this
present report, designed to provide an
overall picture which, while perhaps
over-simplified in the particular details
most familiar to any one reader, will
at the same time give him information
of general interest in other less familiar
fields.

Editor's Note: This report, scheduled for
some time for the Journal, now has special
significance as a summing up by Engineer-
ing Vice-President Bowditch who, because
of new responsibilities at the Research
Laboratories, National Carbon Company,
Cleveland, Ohio has found it necessary to
resign before the expiration of his present
term. He has served the Society as its
Engineering Vice-President since January
1950.

Foremost in the engineering activities
of the Society is of course the work of its
Engineering Committees. From 1 to 75
pages of any individual Journal issue may
be devoted to this field, and a check of
Journals since January, 1950, shows an
average of about 17 such pages per
issue. This includes not only Com-
mittee Reports and the publication of
proposed and final American Standards,
but records of Convention symposia
growing out of Committee deliberations
on such widely different and often
highly controversial subjects as pre-
ferred screen-viewing conditions, pro-
posed magnetic film standards and
16mm emulsion position. A complete
bibliography of Engineering Committee
publications would thus be very exten-
sive indeed, and much too long for in-
clusion here. For this reason, the ref-
erences cited are confined to publica-
tions during the writer's term of office —
except for a few much earlier ones of
historical interest.

The Society prides itself on providing
in these Committees a completely
neutral atmosphere, without com-
mercial bias, where the most active
competitors can get together to work out
their common problems. A more com-
plete statement of the high regard in
which the Society holds its responsi-
bilities here will be found in the policy
statement1 published by the writer
soon after assuming the Engineering

September 1952 Journal of the SMPTE Vol. 59

161

Vice-Presidency in January, 1950. It
will be noted from this that while the
Engineering Committees do determine
appropriate test methods, and sometimes
set limits characteristic of good per-
formance, the Society is never permitted
to become involved in the application
of these to the comparative rating of
competitive merchandise.

As has been implied, a major activity
of the Engineering Committees is the
determination of proposals to be recom-
mended as American Standards. An
American Standard can only be vali-
dated by the American Standards
Association, according to a procedure
which will be described later; but a
great deal of spadework is required to
reconcile competitive viewpoints and
to phrase a proposal combining the
resultant area of agreement with the
technical accuracy necessary to a useful
standard. In motion picture and re-
lated television fields, the spadework
for a particular standard is done by one
of the Engineering Committees of the
SMPTE. This arrangement is a rela-
tively recent one, and much simpler
than before, as will be explained later.
Also, since SMPTE as sponsor of ASA
Sectional Committee PH22 is responsible
for the general organization and work
program of this Committee, the Engi-
neering Vice-President is able to co-
operate effectively within the ASA
toward this same goal of a simplified
Committee organization of maximum
efficiency.

Particularly with the expansion of the
Society's interests into related fields of
television, possibilities for conflict de-
veloped between the agenda of SMPTE
Engineering Committees and those of
other technical societies. This soon
led to the formation of a steering com-
mittee, which now bears the impressive
title "Joint Committee for Inter-Society
Coordination," and is composed of two
delegates each from IRE, RTMA,
SMPTE and most recently NARTB.
The several committees of SMPTE in

television fields have been set up with
the knowledge and guidance of this
group, and their agenda coordinated
with those of potentially conflicting
Committees of the other Societies repre-
sented. Here too an unnecessary burden
was formerly placed upon many indus-
tries asked to contribute the time and
expenses of technical employees to the
Committees of several societies simul-
taneously engaged in solving what
seem to be the same problems. It is
the purpose of the JCIC Committee to
eliminate such waste, at least among the
member Societies. The Chairmanship
of this group rotates among the eight
members on an annual basis, each
Society being represented in turn. Mr.
Axel Jensen started things off last year
as the IRE representative, while the
writer is serving for SMPTE during
1952.

In the following paragraphs the origin
and the work of each of the Society's
Engineering Committees will be de-
scribed in turn. From this it will be
apparent that much besides American
Standards proposals occupies these
groups, and it is hoped that some useful
measure of the important services ren-
dered to the Society and to industry will
be brought out.

Color

This Committee has been con-
tinuously active since its creation in
1929, and is thus one of the oldest com-
mittees of the Society. Dr. Herman
H. Duerr of Ansco has just concluded
two very capable terms as chairman, and
has now been succeeded in this post
by Dr. J. P. Weiss of Du Pont. The
sixteen members of the Committee are
chosen to represent the film and equip-
ment manufacturers, as well as the
studio users of color film. Although no
American Standards have been needed
recently in this field, the Committee
has been actively concerned with such
matters as a color process symposium,
color sensitometry, color film sound

162

September 1952 Journal of the SMPTE Vol. 59

tracks, spectral requirements of light
sources and projection screens and light-
source color measuring instruments as
applied to photography. A subcom-
mittee under Lloyd Goldsmith prepared
a very complete table on "Characteris-
tics of Color Film Sound Tracks,"2 and
another subcommittee under Carl Over-
hage published an excellent 72-page
treatise on "Principles of Color Sensitom-
etry."3 These two examples illustrate
very well the important work in fields
other than standardization which is
being done by the Engineering Com-
mittees of the Society.

Curiously enough, the one proposal
for standardization which this Com-
mittee has received in recent years was
necessarily postponed until the trade
situation is further clarified. It was
pointed out to the Committee that
several sorts of color film are presently
on the market, each balanced for
photography with an incandescent tungs-
ten light source of a different color
temperature. Standardization on a
single color temperature would obviously
provide for simpler stocking of film
and of light sources, and so would seem
a proper subject for consideration by the
Committee; moreover, if the lower color
temperature could be made standard,
lamp life would be much prolonged.
It was soon agreed, however, that
standardization was not appropriate at
this time because many economic factors
remain to be clarified before the best
balance between picture quality, film
speed and light color and intensity can
be determined. The Society has no
right, nor in fact does it have the power,
to force a single standard where sub-
stantial unanimity cannot be secured;
nor are the facilities available to con-
duct extensive technical studies under
Society auspices, and so assume the re-
sponsibility for securing the one best
answer to a complicated problem such
as this one.

C. Francis Jenkins, first president of
this Society, gives excellent precedent

for this present-day action in an address
on "Society History"4 delivered in 1918.
Reporting an unsuccessful attempt "to
adopt an alleged ideal specification for
a projection machine" on account of the
objections "by makers of diverse models,"
he concluded as follows:

"It did one thing, however, well
worth while. It clarified the atmos-
phere and made more distinct to. me
and perhaps to others of us, the objects
for which this Society was organized
and even more strikingly the things for
which it is not organized.

"For example, the Society of Motion
Picture Engineers is not a judicial body
to settle controversies between con-
flicting interests or to promulgate recom-
mendations which make for class-dis-
crimination. If our Society ever de-
generates into a contest between factions
each trying to use the Society for per-
sonal advantage, then our usefulness is
ended and our organization will soon
break up as others in the motion picture
industry have already done.

"What we did organize for was to
set our official seal on standards generally
recognized as standards; and second,
and perhaps best of all, to put into
permanent form for world-wide dis-
tribution, the specialized knowledge
which our members, experts in their
particular line, are so unselfishly furnish-
ing for this purpose. And while the
official stamping of generally acknowl-
edged standards is a necessary duty,
for myself I have found the most interest
in our meetings has come from the
valuable papers read and printed, and
I don't believe the limited time of our
meetings can be spent in a more worth-
while manner."

Film Dimensions

This is a relatively new Engineering
Committee, established in 1948 by the
preceding Engineering Vice-President,
John A. Maurer. The Society has been
active in the field of film dimensions
from the very beginning, however, as

F. T. Bow ditch: Engineering Activities

163

witness the presentation by Donald J.
Bell of a paper on "Motion Picture Film
Perforation" at the meeting of October
2-3 in 1916, the second formal meeting
of the Society. Bell's demand for
standardization started a continuing
activity, through first a "Committee on
Cameras and Perforations" in 1916, then
a "Committee on Film Perforations" in
1921, which continued as a subcommittee
of the Committee on Standards from
1924 to 1948. In line with the philos-
ophy of simplification previously ex-
pressed, the long-standing importance
of film dimensions was once more
recognized, and the former subcom-
mittee was made a full-fledged Engineer-
ing Committee in 1948. Dr. Emmett
Carver of Eastman Kodak has been
the very competent Chairman of this
group since its formation, the members
representing the film manufacturing
companies and those most concerned
with the handling of film through appa-
ratus in which dimensional tolerances
are critical.

The biggest problems facing this
Committee at present are those relating
to the introduction of the new safety-
type film bases. Film is ordinarily slit
to dimension and perforated at the time
of manufacture. After an indeterminate
period of time, involving perhaps pro-
longed storage under various humidities
and temperatures, and chemical proc-
essing, this film must pass smoothly
and with great accuracy of positioning
through a camera, printer, projector or
perhaps some other sort of specialized
film-handling equipment. The critical
dimensions of these equipments have
been chosen by long experience to
match the characteristics of the old-style
film base. Now, with new bases with
different dimensional changes being
introduced, the shoe is on the other
foot: the film manufacturer must alter
his initial slitting and perforating dimen-
sions so that the dimensions in critical
usage will be the same as before. Ameri-
can Standards for film dimensions pres-

ently "apply to the material imme-
diately after cutting and perforating":
the later dimensions at the time of film
passage through an apparatus of some
sort are of course known to be most
important, but to date no one has been
able to visualize a suitable procedure
for extrapolating these back to the time
at which the slitting and perforating is
done.

Another problem of this Committee
has been concerned with the possible
choice of a single preferred shape for
the sprocket perforation of 35mm positive
and negative film. A proposal for this5
has been forwarded to the Committee
on Standards with the recommendation
that it be made an American Standard.

Finally, a recent policy decision in
the field of film dimensioning is worthy
of notice. Not all film is slit at the time
of manufacture. 16mm and 8mm film
stock is sometimes provided double-
width, to facilitate processing, with final
slitting-to-width done after processing.
For one reason or another, a good deal
of the film made in this way has not been
slit with the accuracy in width required
to meet the American Standard di-
mensional tolerances, and poor sound
reproduction, excessive picture weave
and even film jamming in projection
has resulted. The Committee con-
sidered the desirability of preparing a
second and less rigid dimensional stand-
ard for 16mm film, to apply only to film
slit from 35mm or 32mm stock after
processing. This idea was soon re-
jected, however, on the basis that the
present 16mm dimensional specification
is required for interchangeable per-
formance in all equipments, without
reference to the manner in which the
film is made. Thus there is no logical
reason to let down the bars solely for
the purpose of permitting all laboratory-
slit product to qualify under a Standard
of some sort. Since American Standards
are not compulsory, a considerable
market can and often is developed in
nonstandard merchandise of all sorts.

164

September 1952 Journal of the SMPTE Vol. 59

It was concluded, however, that the
demonstration of the existence of such a
market is no reason to dignify it with a
high-quality label.

•Film Projection Practice

No matter what talent and expense
have gone into the preparation of a
fine motion picture film, the film must
finally be projected with proper skill
and good equipment in order to yield
the proper end product. Projectionists
and equipment manufacturers alike
have always recognized this critical
importance of high-quality projection,
ever since this Committee was first
established under the chairmanship of
F. E. Richardson in 1928. Many will
recall the fervent pleas for good pro-
jection practice which were a valued
contribution of Mr. Richardson to the
Convention sessions of more than a
quarter century ago. He was perhaps
more responsible than any other person
for halting the early practice of referring
to the men in the booth as simply
"operators," and seeing to it that the
more appropriate term "projectionist"
came into common usage.6 The torch
is presently being carried by Ralph
Heacock of RCA, who has recently
succeeded M. D. O'Brien of Loew's
in this important Chairmanship. A few
years ago the word "Film" was added
to the name of this Committee, in
recognition of the advent of television
projection in theaters, and the assign-
ment of this latter aspect to the Com-
mittee on Theater Television.

The membership of the Committee
on Film Projection Practice is presently
composed largely of projection equip-
ment manufacturers and theater circuit
representatives, although we would like
to add more projectionists to this group.
An interesting agenda includes revision
of the projection room plans, the possible
preparation of projection room main-
tenance instructions, preparation of a
proposed standard for arc-lamp mount-

ing dimensions and the review of three
American Standards dealing with pro-
jector aperture dimensions, basic pro-
jection room and lens dimensions and
35mm projection reels.

Films for Television

This Committee was first formed early
in 1950, in line with the expanding
interests of the Society in television fields.
Previous to 1950, only two SMPTE
television committees were in existence —
one on Theater Television and one on
simply Television. The latter became
unwieldy as interests broadened, and
so was divided into three Committees,
on Films for Television, Television Film
Equipment and Television Studio Light-
ing, respectively.

The Committee on Films for Tele-
vision is chaired by Dr. R. L. Garman
of General Precision Laboratory, and
is staffed by film, equipment and
television studio representatives. The
committee is concerned with the special
problems of film as used in television,
and has been especially active in the
field of "Television Test Films"7 which
has presented some very difficult prob-
lems, and in the preparation of a "New
All-Pur pose Film Leader"8 by a very
capable and energetic subcommittee
led by C. L. Townsend of NBC. Other
projects include a study of the problems
concerned with pictorial quality of films
for television use, and a study along with
other Committees of the long-standing
problem of 16mm emulsion position.9
The reference noted should be consulted
by those interested in this problem.
The television picture and sound prob-
lems arising from the indiscriminate use
of film for projection with emulsion
sometimes facing the light source and
sometimes the lens, was thoroughly dis-
cussed during the October 1951 Con-
vention in Hollywood.10 It was agreed
then that it is up to the purchaser to
specify and pay for the emulsion position
he wants, and some television studios

F. T, Bow ditch: Engineering Activities

165

report very good success in this way.
The Hollywood symposium on 16mm
emulsion position is worthy of special
mention here as a typical example of
an engineering service growing out of
Engineering Committee activity.

High-Speed Photography

This Committee was first organized
by Engineering Vice-President John A.
Maurer in 1 948, with John H. Waddell
as Chairman and with a membership
representing film and equipment manu-
facturers along with an excellent repre-
sentation of the users of this very special-
ized equipment. Under Waddell, this
group got off to a most energetic start,
although more along the lines of a
Papers Committee in its field, rather
than with an agenda of engineering
problems to be solved as is the case
with the other Engineering Committees.
In the papers field, the Committee on
High-Speed Photography has sponsored
technical sessions for one or more days
at several Conventions and has published
"A Survey of High-Speed Motion
Picture Photography" and a "Bibliog-
raphy on High-Speed Photography,"11
while sponsoring the "High-Speed Pho-
tography Question Box."12 A "Sub-
committee on Technical and Engineer-
ing Society Liaison" was organized last
year with representatives from about
twelve other technical organizations,
although it is too early to judge what
may come from this attempt to correlate
all technical-society effort in this field.

When John WaddelPs permissible
limit of two terms (four years) as Chair-
man terminated last January, we were
fortunate in securing the services of Dr.
Harold E. Edgerton of M.I.T. in this
post. With the planning of an Inter-
national Symposium on High-Speed
Photography for the Washington meeting
next October, the Committee is con-
tinuing its typically fast pace along this
line.

Laboratory Practice

This is another of the Society's long-
standing Committees, organized first as
a committee on Laboratories in 1921,
then Development and Care of Films in
1931, Laboratory and Exchange Prac-
tice in 1933, and finally as a separate
Committee on Laboratory Practice since
1935. This Committee has never oper-
ated with more energy and effective-
ness than during the last few years
under the Chairmanship of John Stott
of Du-Art Film Laboratories. Member-
ship is recruited largely from the proc-
essing laboratories, as the title would
suggest.

Projects of this group include the
determination of a standard screen
brightness for 16mm review rooms, so
that the customer and the laboratory
may judge the product on an agreed
common basis. Difficulties presently
arise here on account of the conflicting
demands of the Armed Services for thin
prints to be projected at low light levels,
and the need for dense prints for the
amateur's small, beaded screens and
1000-watt projection lamps.

The standardization of printer cueing
devices is another project of much po-
tential value. Negatives circulate widely
between laboratories and since there is
no present agreement respecting these
cueing devices, much patching and
mutilation of the film results.

Emulsion position with 16mm posi-
tive films has also been discussed long
and often by this group. Here too it is
concluded that no single standard will
ever be observed until the customers
apply the necessary pressure and agree
to pay the extra cost where this is in-
volved. Standard magnification ratios
when printing between 35mm and
16mm film sizes, and assistance to the
Armed Services in setting up better
specifications for print quality are other
problems. The recent establishment
of a Chemical Corner13 in the Journal is

166

September 1952 Journal of the SMPTE Vol. 59

another important service provided by
this Committee.

Motion Picture Studio Lighting
and Process Photography

A Society committee on Studios was
first organized in 1917, followed by one
on Studio Lighting in 1928, which has
operated continuously since that time.
The term "Motion Picture" was added
to the Committee title in 1950 to dis-
tinguish this from the newly created
Television Studio Lighting Committee.
A former Committee on Process Photog-
raphy was combined with the Studio
Lighting Committee in 1951, following
a six-year period of carrying the former
on the books as "under organization,"
with little evidence that such organiza-
tion was really needed.

This illustrates another basic principle
of Engineering Committee operation.
These Committees come and go — and
perhaps return again — as the needs
of the industry require. There is never
any intention to carry a Committee
simply as a listing of names in the
Journal, and such a listing is terminated
as soon as reasonable efforts to stimulate
activity prove unsuccessful. Activity
solely for activity's sake is never en-
couraged; but if there is useful work to
be done, every effort is made to enlist
competent persons to do it.

M. A. Hankins of Mole-Richardson
has recently concluded a very competent
two-term maximum as Chairman of the
Committee on Motion Picture Studio
Lighting and Process Photography, and
he is now succeeded in this post by
John W. Boyle, Director of Photog-
raphy. This group is based in Holly-
wood, and is composed of studio lighting
equipment representatives and persons
who are concerned with set lighting.
Since the proper use of lighting is largely
a matter of art, the field of the engineer
is limited here. In spite of this, the
Committee regularly prepares compre-
hensive reports14 which are most useful
in acquainting the industry with the

latest things in set illumination equip-
ment and their studio usage.

Another motion picture studio group,
the Committee on Cinematography,
also based in Hollywood, was temporarily
inactivated a year ago, after no interest
had been manifest for a considerable
number of years.

Limited West Coast activity in Society
Engineering Committee work is no doubt
in part the result of basing the Engineer-
ing direction almost 3000 miles away,
in the New York headquarters of the
Society. Another factor, of course, is
the fine work of the Motion Picture Re-
search Council and * of the American
Society of Cinematographers in related
fields. The Society enjoys the best
possible cooperation with these organi-
zations, and of course has no interest
in attempting to duplicate their work.
Nevertheless, the Engineering Vice-
President has repeatedly felt a sense of
responsibility to encourage more activity
in the West Coast committees which are
part of the traditional engineering
organization of the Society. Any sug-
gestions here will be most welcome.

Optics

Reference to the first volume of the
Transactions of our Society indicates a
very early interest in the subject of
optics, a Committee on Optics having
been formed in October 1916 and re-
maining active through 1923. From
1930 through 1934 a Committee on
Projection Theory was concerned with
this field, but this was absorbed by the
Committee on Standards in 1935.
Finally, a subcommittee of the Com-
mittee on Standards was once again
given full committee status in 1950 with
the establishment of the present Com-
mittee on Optics. Dr. R. Kingslake
of Eastman Kodak has served as Chair-
man since that date.

The first major assignment of this
Committee has been the preparation of
a proposed standard for the photometric
calibration of camera lenses. The group

F. T. Bowditch: Engineering Activities

167

has agreed on two methods, either of
which gives accurate results. A recom-
mendation has also been submitted
respecting the standardization of an
associated lens marking system in so-
called "T-stops," but this portion of the
proposal is finding considerable opposi-
tion from those who feel that the valida-
tion of a T-stop lens marking method
will lead amateurs to expect a greater
exposure accuracy than will likely result.
The Committee has done a very excel-
lent technical job in specifying accurate
calibration methods, a procedure which
has been much facilitated by the
generosity of the Radio Corporation of
America in granting licenses under a
patent issued to L. T. Sachtleben of
RCA. If the T-stop versus /-stop
controversy proves insoluble, it is hoped
that the test methods can in some way
be made standard, independent of the
provocative term "T-stop."

Other projects of this group include
the specification of lens mounting dimen-
sions for 35mm, 16mm and 8mm film
projectors, and standard lens resolution
test procedures.

Screen Brightness

The present Screen Brightness Com-
mittee dates back to the Committee
on Theater Engineering of 1941. This
latter Committee consisted at that time
of a combination of several subcom-
mittees, including one on Screen Bright-
ness. This subordinate status con-
tinued through 1945, after which the
several subcommittees of the Theater
Engineering Committee were each given
full Engineering Committee status. Dr.
W. W. Lozier of The National Carbon
Company is the present Chairman of
this very active group.

A major activity here has been the
screen brightness survey,15 which has
now been extended to cover 125 indoor
theaters and 1 8 West Coast 35mm review
rooms. Much helpful information has
been secured, and this is being extended
to include a representative number of

drive-in theaters. An important aspect
of this work has been the specification of
a suitable light-measuring equipment
and method of use.

A symposium on screen viewing fac-
tors16 was sponsored by this Committee,
providing not only a most instructive
Convention session but also more than
50 pages of technical papers in the
Journal. The great importance of these
screen viewing factors is fully recognized
by the Committee, which is presently
working to stimulate commercial in-
terest in the psychological test pro-
cedures required to get the audience
reaction data needed.

A basic problem in standardization
recently developed when a question
arose respecting the omission of drive-in
theaters from the American Standard
specification of screen brightness (101J
ft-L). No commercial projection equip-
ment can presently supply, nor will
present film withstand, the quantity of
light required to illuminate large drive-in
screens to this level. So, no matter
how good his intentions, the owner of a
drive-in can only meet the present
American Standard by cutting the size
of the screen and the capacity for
customers to an impractical extent.
Rather than give a "nonstandard" label
to all the drive-in theaters in the coun-
try, the Committee therefore voted to
omit them altogether from the speci-
fication. This is in line with the basic
principle that an American Standard
should be a commonly accepted practice,
capable of realization in a commercial
way, and not simply a theoretical
quality goal for the indefinite future.

The Screen Brightness Committee
now has active Subcommittees on:
Meters and Methods of Measurement,
Projection Screens, and Illumination
Practices.

16mm and 8mm Motion Pictures

This group was first organized as the
Committee on Nontheatrical Equipment
in 1931, assuming its present title in

168

September 1952 Journal of the SMPTE Vol. 59

1946, in recognition of the growth of
16mm usage to include important
theatrical as well as many other signifi-
cant high-quality applications. Be-
cause there is much less film area than
with 35mm film on which to record
picture and sound information, the
16mm engineers are encouraged to seek
the best possible quality in all their
operations. Learning in this way what
careful attention to quality can produce,
these engineers have made of this Com-
mittee a very active forum for the ex-
change of ideas and information, and an
effective influence for higher quality
in all phases of the industry.

This interest in all phases calls atten-
tion to the fact that this Committee is
the only one set up along product rather
than along process lines, so that oppor-
tunities for conflict with the work of
the other committees frequently arise.
For instance, problems in 16mm film
dimensions, laboratory practice, sound,
etc., might equally well be handled by
the committees in these particular fields.
This situation has developed from the
early days when 16mm was regarded as
"substandard," and no one even thought
of 8mm film. 35mm sound engineers,
as an example, had no interest in
16mm, so that two entirely different
groups of people were required to
represent those interested in the 35mm
and 16mm applications respectively.
Now that this is no longer true, tradition
and a very active record of accomplish-
ment have operated to maintain a com-
mittee which would probably not be
reorganized at all if we were to ruthlessly
start over again in the light of the present-
day committee arrangement. However,
no Society would be foolish enough to
disband or even to limit the work of a
group as active and as useful as this one
continues to be.

This Committee in recent years has
done an outstanding job of developing
American Standards proposals, a total
of approximately 20 being presently in
various stages of negotiation through

final confirmation. Much of this has
come from intensive work with the
Armed Services during World War II,
directed toward the determination of a
JAN (Joint Army-Navy) specification for
a 16mm projector.

In addition to being the most active
Committee in the development of stand-
ards proposals, the 16mm and 8mm
group is working on recommendations
for 16mm review rooms, especially
sound reproducing equipment, a test
film for checking the resolution of
projector optical systems, and the prepa-
ration of a booklet on 1 6mm and 8mm
Projection Practice.

The Committee has been faced with
many difficult standardization problems,
in some of which unanimous trade
agreement has been impossible to
achieve. The familiar one of 16mm
emulsion position is an outstanding
example; although an American Stand-
ard does exist here, this is frequently
ignored and serves mainly to demonstrate
the futility of a Standard which does not
have the acceptance of all concerned.
Another classic case is the specification
of the guided edge in several standards
dealing with 16mm film. Projector
manufacturers were not in agreement
in their choice of the sound-track versus
the perforated edge, since good design
reasons existed for either one. Now,
however, a reversal of the earlier ma-
jority opinion is in prospect, on account
of the prevalence of increasing amounts
of substandard 1 6mm film, inaccurately
slit from 32mm or 35mm after proc-
essing, and so providing a very inac-
curate reference edge for the positioning
of the picture and sound-track areas.

Present-day difficulties in arriving at a
standard here are reminiscent of Mr.
Jenkin's experiences with the first
standardization efforts of the Society,
which were previously quoted. Stand-
ards defining a preferred design for
quality reasons create many debatable
issues, and these should ordinarily be
left for independent resolution by each

F. T. Bowditch: Engineering Activities

169

designer, where critical interchange-
abilities are not involved. Let the
Society specify standard test methods,
including test films, so that the customer
may determine matters of relative
product quality in a reliable manner;
but let us avoid labeling any particular
product as substandard except where
critical interchangeability is involved,
or complete unanimity achieved.

A final example of this kind is the
effort made in 1948 to revise an earlier
American Standard for 16mm sprocket
design, including features intended to
insure better quality rather than simply
interchangeability. Sprockets of a de-
sign different from that of the proposed
standard were stated by a major manu-
facturer to be in wide successful use, and
his engineers did not agree that the de-
sign proposed as standard was any
better than this. Further, to quote E.
W. Kellogg17 ". . . if a manufacturer
puts out a machine which performs well
with a standard film, and the film is
not subjected to undue wear, and his
customers are happy . . . it is no one
else's business what shape tooth he
uses." Thus the difficulties first ex-
perienced by Mr. Jenkins returned to
trouble us once more. In the sprocket
case, the Committee on Standards
adopted a form of recommendation,
which would permit competent tech-
nical material of this sort to be published
in an authoritative manner for the
general education of the industry, while
at the same time avoiding the applica-
tion of a nonstandard label to all other
designs. This form of publication18 is
reserved for standards proposals which
fail to secure the unanimity necessary
for standardization, but which do em-
body much good technical material,
thought to be of general trade interest.

Henry Hood of Eastman Kodak has
just concluded a very capable 4-year
term as Chairman of the 16mm and 8mm
Motion Pictures Committee and has
now been succeeded by Malcolm Towns-

ley of Bell & Howell. The large
membership of 23 persons reflects the
wide range of interests represented.

Sound

When talking motion pictures arrived
with startling suddenness in the late
1920's, they brought many technical
problems, and with them, the creation
in 1930 of the SMPE Committee on
Sound. This is presently the largest
of all the Engineering Committees,
including 27 persons with the Chairman
(West Coast) and Vice-Chairman (East
Coast). Representatives of the 35mm
studios, the 16mm and 8mm industries,
and television combine with the sound
equipment, film and magnetic tape
suppliers to give a very complete cover-
age of the field. Lloyd T. Goldsmith
of Warner Bros, has just completed four
very competent years as Chairman, and
he has now been succeeded by John
Hilliard of Altec-Lansing — also of Hol-
lywood. Glenn Dimmick of RCA con-
tinues as Vice-Chairman in the East,
and in his Chairmanship of the very
important Magnetic Subcommittee.

Major problems in this group have
to do with standardization, particularly
respecting magnetic sound. A very
important symposium respecting mag-
netic film standards was sponsored
during the Hollywood convention last
October19 giving opportunity for a very
frank and open presentation of the
opposing viewpoints. Here is a case
where the need for a single standard
was recognized by all concerned, al-
though each conflicting system had been
chosen by its sponsor for reasons thought
to be valid. The invaluable oppor-
tunity offered by the Society as an
impartial meeting ground for active
competitors is well illustrated here, and 1
there is every reason to anticipate the
early determination of the single standard
needed.

In addition to active work on many
standards, the Sound Committee does

170

September 1952 Journal of the SMPTE Vol.59

a great deal of work on test films, being
presently concerned with the specifica-
tion of new ones related to magnetic
sound.

Standards Committee

This is the most venerable and honor-
able of all the Engineering Committees,
going back to the very early days of the
Society. Standardization in the first
years was "Adopted in Committee of
the Whole Society," as witness the first
"Motion Picture Standards" published
in the first volume (1916-1920) of Society
Transactions.™ These apparently re-
sulted from the recommendations of
one of the four engineering committees
of that time, in fields of Cameras and
Perforations, Motion Picture Electrical
Devices, Projection Machines, and Optics,
respectively. In 1924, a Committee on
Nomenclature and Standards was
formed, this being changed to the present
title in 1934.

For many years, standardization pro-
posals were developed by subcommittees
of the Standards Committee, by sub-
committees of ASA Sectional Com-
mittee PH22 on Motion Pictures and
by any one of the several Engineering
Committees of SMPTE. This finally
led to the realization that the most
competent people in particular fields
have already been brought together in
the respective Engineering Committees
of SMPTE, so that it is most efficient to
refer all Standards work projects directly
to these Committees, rather than to
appoint members of these same Com-
mittees as a subcommittee of the Stand-
ards Committee or of ASA Sectional
Committee PH22.21 This procedure was
first inaugurated by John A. Maurer
and was further facilitated by his ap-
pointment of all Engineering Committee
Chairmen as members of the Standards
Committee. The balance of the Com-
mittee serves ex officio, and includes a
representative of the Motion Picture
Research Council, the chairman of ASA
Sectional Committee PH22, the Past

Engineering Vice-President of SMPTE
and the Past Chairman of the Standards
Committee. This insures a most compe-
tent and experienced group of engineers,
well qualified to handle the policy-type
matters which come before it, along with
the processing of standards proposals.
While the basic policies which are cited
as examples throughout this report are
the responsibility of the Engineering
Vice-President, these are in general the
result of discussions with the Standards
Committee, and the determination of a
consensus there.

The dean of the motion picture
standards business is generally recognized
to be Dr. Emmett Carver of Eastman
Kodak, who served as Chairman of
this Committee for many years. Dr.
Carver brings a very fine attitude of
patience, impartiality and technical
thoroughness to these deliberations, and
his capabilities are universally respected
by those who work with him in this
field. Frank E. Carlson of General
Electric has just completed a competent
four-year term as Chairman of the
Standards Committee, and has now
been succeeded by Henry Hood of
Eastman Kodak. Hood's recent ap-
pointment to fill the remainder of the
current Engineering Vice-President term
creates a vacancy here which has not
been filled at this writing.

Stereoscopic Motion Pictures

The April 1952 Journal was the first
to list this new Committee, formed
since the first of this year. Started a
few months ago as a task force to report
on the extent of trade interest in the
formation of such a permanent Com-
mittee, the group found the response
was immediate and very enthusiastic.
John A. Norling is the ambitious Chair-
man of this new Committee, and while
it is too early to predict the relative
importance and permanence of this
group, present indications are certainly
favorable. Two projects presently under
way are concerned with stereoscopic

F. T. Bowditch: Engineering Activities

171

nomenclature and with the preparation
of a bibliography ol this field.

Joint RTMA-SMPTE Committee
on Television Film Equipment

This Committee is an outgrowth of
negotiations in the Joint Committee on
Inter-Society Coordination. As pre-
viously noted, the SMPTE realized late
in 1949 that television interests in the
Society had grown too large to be con-
tained within the Committees on Tele-
vision and on Theater Television. The
latter was specific enough, but the
handling of all other interests in a
single Committee on Television was no
longer practical. A few months prior
to any definite action by SMPTE, the
RTMA independently realized the need
for technical committee activity in the
field of television film-handling equip-
ment, and so formed a very capable
Subcommittee of Subcommittee 4 of
RTMA Committee TR4, bearing the
designation TR4.4.2. Thus, while
SMPTE was making up its mind, the
independently conceived RTMA Sub-
Subcommittee came into being, squarely
in one of the fields contemplated by
SMPTE, and immediately gave evi-
dence of energetic competence. The
individual members of the RTMA
committee might just as appropriately
have been serving with SMPTE, since
the same commercial" organizations and
most often the identical persons are the
ones most logically chosen whenever a
competent Engineering Committee is
formed in a specific field such as this
one. As an example, seven of the
twelve -man TR4.4.2 Committee were
already SMPTE members, including the
Chairman. Thus it was quite im-
practical for SMPTE to attempt the
formation of an altogether different
Committee to do this same job, even
though this was obviously in a technical
field where the Society was most expert.
Hence the formation of the coordinating
Committee, and the agreement with
RTMA that this would henceforth be-

come a joint committee of the two So-
cieties. Details remain to be worked
out, since the formal procedures re-
specting membership appointment and
chairman selection are not the same in
the two sponsor organizations. Here
too the JCIC will prove helpful.

Dr. Frank N. Gillette of General
Precision Laboratories continues as
Chairman of the Joint Committee, with
Dr. E. C. Fritts as Vice-Chairman,
representing SMPTE. To the original
membership of 12, appointed by RTMA,
SMPTE added six more, from film and
film equipment agencies not previously
represented. A major project of this
group is the preparation of a 16mm
projector specification, incorporating the
special requirements of television usage.
Other projects include a standards
proposal for dimensions of slides and
opaques, and one for picture dimensions
on 16mm and 35mm motion picture
film.

It should be mentioned here that
among the new Committees originally
considered by SMPTE in the field of
television was one on Video Recording,
listed as "under organization" in the
April, 1950, listing of Committees of
the Society. In discussions of this in
the JCIC, it was agreed that aspects
of this operation of interest to SMPTE
would properly come before the Com-
mittees on Film for Television and
Television Film Equipment. The
SMPTE Committee on Video Record-
ing was thus allowed to disband before
the organization phase was completed.
An IRE Subcommittee on Video Sys-
tems and Components is in potential
conflict here, but it has been suggested
through the JCIC that this latter group
do no work on film handling equipment.

Television Studio Lighting

This is another of the new television
committees resulting from the expansion
of the old Committee on Television.
Since this field is not in potential con-
flict with the technical committee work

172

September 1952 Journal of the SMPTE VoL 59

of the IRE, RTMA and NARTB, this
has been agreed to be outside the field
of interest of the JCIG.

The Society has, however, been
engaged in a running argument with
The Illuminating Engineering Society
respecting duplication of effort here,
which was resolved for a while by an
IES agreement to leave this to SMPTE,
while working in IES with the lighting
problems associated with television view-
ing. This agreement has since been
abandoned, however, so that two sepa-
rate technical committees of quite
similar membership presently exist in
the field of television studio lighting,
one sponsored by SMPTE and one by
IES. We have recently explored the
possibility of reducing this to a single
Joint Committee of the two Societies,
as with Television Film Equipment,
but this has so far been unsuccessful,
and further efforts have now been
abandoned.

It has been accepted as a basic policy
of the SMPTE Committee that only
those projects shall be undertaken
which are of admitted interest to the
television studio engineers. Equipment
makers and other suppliers of the
studios are in the minority on the Com-
mittee, and serve primarily as sources of
information.

Richard Blount of General Electric
is serving his second term as Chairman
of this Committee, and is presently
active in promoting the chosen Com-
mittee objectives of: (1) defining means
for the measurement of television studio
lighting, both incident and reflected;
(2) terminology; and (3) the possible
standardization of electrical plugs.

Test Film Quality

This Committee was first organized
in 1944, in order to provide expert
advice respecting the maintenance of
proper quality of the Society's test
films.

Responsibility for defining the content
of one of these test films lies ordinarily

with the Engineering Committee most
concerned, as does the suggestion of new
test films as their need becomes ap-
parent. The Quality Committee, on
the other hand, sees to it that appro-
priate controls are devised and main-
tained to insure that the films made are
in accordance with these specifications.
With the full time employment of Fred
Whitney about one year ago, Society
headquarters facilities for test film
quality maintenance have been much
augmented.

The present Chairman of this im-
portant Committee is Fred Pfeiff of
Altec Service Corp., who is exceptionally
well acquainted with test film quality
considerations from the user's standpoint.
The Committee membership consists of
persons expert in the processing of high
quality film, including a representative
of the Motion Picture Research Council.

Theater Television

This Committee was first organized
in 1944 as a Subcommittee on Tele-
vision Projection Practice of the Com-
mittee on Theater Engineering, acquir-
ing the present title of "Theater Tele-
vision" in 1948. The group has oper-
ated to date largely as a policy Com-
mittee, and for the purpose of assembling
and distributing technical information
of interest in this important new field.
The Society has also appeared before
the Federal Communications Commis-
sion, presenting data secured through
this Committee relating to the nature
of the facilities thought necessary for a
theater television distribution system.22

Largely as the result of the stimulation
provided through this Committee, many
business groups became actively in-
terested in theater television, and these
have also appeared with increasing
enthusiasm before the FCC in support
of this new medium. Finally, it became
apparent that the services of the Society
were no longer needed to plead this
cause, and the Theater Television Com-
mittee recommended that the Society

F. T. Bowditch: Engineering Activities

173

make no further appearances before
the FCC since "the new industry is well
able to solve its own- commercial problems "
The statement "Theater Television and
the FCC,"23 should be consulted for
further details.

It is anticipated that this Committee
will some day be concerned predomi-
nately with the engineering problems
arising from the operation of television
projection equipment in theaters. Con-
sideration is also being given to under-
taking a study of color television systems
as applied to theater use. For the
moment, things must stand by until
the oft-postponed FCC hearings are
out of the way, since these must occupy
the first interest of many of the Com-
mittee members. Results of these hear-
ings will also have an important effect
on the future field of interest of the
group.

Paul J. Larsen was the chairman of
this Committee during the very im-
portant formative years from 1945 to
1 948, and his missionary enthusiasm
did much to keep the spark alive when
commercial interest waned. Donald
E. Hyndman took over in 1948 and
brought Larsen's early work up to the
point where trade enthusiasm became
so great that no further Society par-
ticipation before FCC was needed.

George L. Beers of RCA is the present
Chairman, and in talking his assignment
over with the Engineering Vice-Presi-
dent and with Mr. Hyndman (who was
forced to resign on account of the pres-
sure of other affairs) the following
general field of operation was agreed
upon:

"In general the Theater Television
Committee should concern itself with
the study of the engineering factors
involved in the production of theater
television programs. Rather than at-
tempt to prescribe the minimum picture
quality which a theater television screen
image must provide in order to be a
sales-worthy product, the Committee
should indicate the engineering require-

ments of systems of different quality.
In this way the theater industry can
have the technical information needed
on which to base its own course of com-
petitive action.

"It was pointed out, however, that
in spite of our intent to operate pri-
marily as an engineering group, the
crystal-gazing aspect might, neverthe-
less, be requested of us by the FCC.
In such an event, an opinion would of
course be determined, but in such a way
as to distinguish it clearly from the
factual engineering data which are to
be the main concern of the Committee."

Theater Engineering

Society committee work in this field
has been carried on from the very be-
ginning, starting as a Theater Equipment
Committee in 1916. From 1940 to
1945 the Theater Engineering Com-
mittee provided general directional re-
sponsibility for several major Sub-
committees which later became full
fledged Engineering Committees, i.e.,
Projection Practice, Screen Brightness,
Television Projection Practice, etc. The
Committee on Theater Engineering Con-
struction and Operation was one of
these to become separately established
in 1946, with this long title shortened
to the present one of simply Theater
Engineering in 1949.

Leonard Satz of Raytone Screen Corp.
served capably as Chairman of this
Committee, starting in 1948; the present
chairman is J. W. Servies of National
Theater Supply. Projects studied by
this group include theater carpets,24
air-conditioning, size and mounting
characteristics of theater screens, and
theater codes. A correlation of the
latter as among the several states and
cities would be of very great service to
industry, and might promote worth-
while standardization.

Thus is concluded the description
of the 18 Engineering Committees
presently operating for the SMPTE.

174

September 1952 Journal of the SMPTE Vol. 59

Further along engineering lines, the
Society is a member of the Inter-Society
Color Council and is represented there
by a delegation of which Ralph M.
Evans of Eastman Kodak is Chairman.
Society representation is similarly pro-
vided on the U.S. National Committee
of the International Commission on
Illumination, with Ralph Farnum of
General Electric as Chairman. The
most extensive of these extra-society
engineering activities, however, is that
with The American Standards Associa-
tion, this being discussed in the following
paragraphs.

American Standards Association

This is an association of standardizing
bodies in many fields of industry,
sponsored by industry, and issuing so-
called American Standards. These
Standards do not of themselves have
any force in law, but are generally
recognized as representing best practice,
and so are frequently incorporated in
purchase specifications by agreement
between individual buyers and sellers.
Elaborate safeguards are provided in
the preparation of these standards,
insuring the very careful review of all
standards proposals by a sequence of
authorities terminating in a Standards
Council. Provision is also made for
the periodic review of all existing
American Standards so that obsolete
material does not remain on the books.

Standards in the field of motion pic-
tures and in those aspects of television
assigned the Engineering Committees of
SMPTE are processed through ASA
Sectional Committee PH22 on Motion
Pictures, presently under the chairman-
ship of Dr. D. R. White of Du Pont.
This ASA Committee is authorized to
consider proposals received from any
reputable source, but, in practice,
almost all of these originate in SMPTE
or in the Motion Picture Research
Council. In line with the simplification
previously discussed, Committee PH22
seldom conducts a technical study in the

entire Committee, since the representa-
tion is necessarily so broad that adequate
technical coverage of any one specialized
field is not possible. Subcommittees
used to be created to enlist such talent
as needed, but this is now handled
through the Engineering Committees
of SMPTE. Thus with respect to the
processing of American Standards, Com-
mittee PH22 is largely a policy group,
concerning itself more with the need
for a particular standard and whether
or not an adequate consensus has been
reached, rather than with the technical
content.

With the recently increased interest
in world standards through Technical
Committee 36 on Cinematography of
the International Organization for
Standardization (ISO/TC36), PH22 has
now assumed an important new re-
sponsibility. The Secretariat of this
International Committee is held by the
ASA, and the responsibility for express-
ing the U.S. viewpoint, both respecting
world standards proposals and in reply-
ing to the proposals of other nations,
naturally channels through PH22.
Policy matters are decided there, and
technical studies requested of the
SMPTE Committees where needed.
The first international meeting of ISO/
TC36 was held in New York City on
June 9, 10 and 11, 1952, with PH22
playing an important part in heading
the U.S. delegation. U.S. proposals for
consideration as International Standards
were first recommended by the Engi-
neering Committees of SMPTE, and the
Chairmen of the committees concerned
with these recommendations were in-
cluded in the U.S. delegation headed
by Dr. White. The Engineering Vice-
President of SMPTE was chosen as
chairman of this first formal meeting of
ISO/TC36, and is most appreciative
of having been given this opportunity
to work with this very sincere and
highly cooperative group. Delegates
from Belgium, France, Germany and the
United Kingdom worked with the U.S.

F. T. Bowditch: Engineering Activities

175

group here to achieve substantial
unanimity respecting a much greater
number of so-called Draft Proposals
than anyone had thought possible.

Committee PH22 derives its authority
from two sources. First, the Com-
mittee is "sponsored" by the SMPTE.
This is a conventional arrangement,
typical of many other ASA Sectional
Committees. The sponsor is responsible
for the agenda, and submits his recom-
mendation to ASA respecting the chair-
man. He is ordinarily required to
supply secretarial service, which is very
capably done for PH22 by the very
versatile Henry Kogel, SMPTE Staff
Engineer. Kogel is unusually well fitted
for this task, since he also serves as
secretary for all the Engineering Com-
mittees of SMPTE, previously described.

Within the ASA structure, Com-
mittee PH22 is one of five Sectional
Committees under the general juris-
diction of a Photographic Standards
Board (PSB), of which Paul Arnold of
Ansco is the Chairman. The other Com-
mittees in this group are:

PHI, Photographic Films, Plates and

Papers;

PH2, Photographic Sensitometry;
PH3, Photographic Apparatus; and
PH4, Photographic Processing.

These four represent divisions of the
earlier ASA Sectional Committee Z38
on Photography, which became too
cumbersome in its operations to con-
tinue as a single group. When this
reorganization of Z38 into four separate
Committees was under consideration
by the ASA, the creation of a new
correlating Board was also proposed,
to which these new PH committees
would report in a manner conventional
in the ASA with other groups. The
SMPTE was asked to agree to a revision
of the then independent status of ASA
Sectional Committee Z22 on Motion
Pictures, so that it too would report
to the new correlating Board. This
was agreed to, and the designation

accordingly changed from Z22 to PH22.
Objections were raised at the time to
inserting another in the long chain of
reviewing agencies between the technical
working body on the one end and the
Standards Council on the other. How-
ever, SMPTE received assurance from
the ASA that this was purely an organi-
zational detail within ASA, and that
the new Correlating Committee would
exercise no significant authority over
the affairs of PH22. Correlation is
naturally required at some stage to
prevent possible duplication of effort
between PH22 and the four other PH
Committees, and this the new Photo-
graphic Standards correlating Board
does with very good effect all around.
Thus while the rules of procedure of the
ASA give correlating Boards in general
the right to exercise a considerable degree
of authority, this is frequently not used,
and it is anticipated that the existence of
the PSB will have little effect on the
operations of PH22, so long as the
SMPTE does a competent job as
sponsor.

This then is the present picture of the
activities in which the Engineering
Vice-President represents the interests
of the SMPTE. It is a continual
pleasure to work with such a fine,
cooperative group of technical people,
and particularly with the very refreshing
international experience with ISO/
TC36 so clearly in mind, it seems
altogether tragic and unnecessary that
similar progress is not made along
political lines. The scientists, however,
are showing an ever increasing concern
in the study of human reactions, for
example in their interest in many phases
of the science of color, and the determi-
nation of preferred motion picture
viewing conditions — so they may yet
bring their talents and impartial scien-
tific viewpoints to bear on the trouble-
some social problems of the world.
Having seen the fine cooperative give-
and-take in our many Committees, with

176

September 1952 Journal of the SMPTE Vol. 59

axe-grinding at a negligible minimum,
one is at least led to hope.

Finally, I wish to express my great
indebtedness to the several Chairmen
mentioned previously, and to the almost
300 Committee members, whose un-
selfish cooperation has made this work
possible; also, to Society headquarters
where Boyce Nemec maintains a most
efficient organization and Henry Kogel
strives manfully and with very good
effect to keep on top of his even score
(or is it more?) of secretarial responsi-
bilities. The contribution of my own
employer, The National Carbon Com-
pany, in granting me the time and
expense monies necessary to the conduct
of this very pleasant work, is also grate-
fully acknowledged.

References

1. "A restatement of policy," Jour.
SMPTE, 54: 233, Feb. 1950.

2. "Characteristics of color film sound
tracks," ibid., 54: 377, Mar. 1950.

3. "Principles of color sensitometry,"
ibid., 54: 653-724, June 1950.

4. C. F. Jenkins, "Society history,"
Trans. SMPE, No. 7: 6-8, Nov. 1918.

5. W. F. Kelley and W. V. Wolfe,
"Recent studies on standardizing the
Dubray-Howell perforation for uni-
versal application," Jour. SMPTE,
56: 30-38, Jan. 1951; W. Hill,
"Modified negative perforation," ibid.,
57: 108-123, Aug. 1951; "Proposed
American standard," ibid., 57: 275-
278, Sept. 1951.

6. F. H. Richardson, "Projection room
and its requirements," Trans. SMPE,
No. 7: 29-37, Nov. 1918.

7. "Television test film," Jour. SMPTE,
54: 209-218, Feb. 1950.

8. C. Townsend, "New all-purpose film
leader," ibid., 56: 562-567, May 1951.

9. "Recent American standards for 16
and 8mm emulsion position," Jour.
SMPE, 49: 547-557, Dec. 1947.

10. "Panel discussion on emulsion position
of 16mm positives," Norwood Sim-
mons, Moderator, SMPTE Conven-
tion, October 17, 1951. A mimeo-
graphed transcript, 46 pp., is available
upon request to Society headquarters.

11. K. Shaftan, "A survey of high-speed
motion picture photography," Jour.
SMPTE, 54: 603-626, May 1950;
"Bibliography on high-speed photog-
raphy," ibid., 56: 93-111, Jan. 1951.

12. "High-speed photography question
box," ibid., 55: 122, July 1950; ibid.,
55: 328, Sept. 1950.

13. "Chemical corner," ibid., 57: 87-88,
July 1951; ibid., 58: 272-273, Mar.
1952.

14. M. A. Hankins, "Motion picture studio
lighting committee report," ibid., 56:
205-213, Feb. 1951.

15. W. W. Lozier, "Screen brightness
committee report," ibid., 54: 756-757,
June 1950; "Report on screen bright-
ness committee theater survey," ibid.,
57: 238-246, Sept. 1951; "Further
report on screen brightness committee
theater survey," ibid., 57: 489-493,
Nov. 1951.

16. "Symposium on screen viewing fac-
tors," ibid., 57: 185-237, Sept. 1951.

17. "Proposed 16mm and 8mm sprocket
standards," Jour. SMPE, 51: 437-440,
Oct. 1948.

18. "Recommendations for 16mm and
8mm sprocket design." Jour. SMPTE,
54: 219-228, Feb. 1950.

19. Loren L. Ryder and Bruce H. Denney,
"Magnetic sound track placement,"
Jour. SMPTE, 58: 119-136, Feb. 1952
(includes Discussion, pp. 127-136).

20. "Motion picture standards," Trans.,
SMPE, No. 4: 8-9, July 1917.

21. F. T. Bowditch, "Report of SMPE
standards committee," Jour. SMPE,
51: 230-241, Sept. 1948.

22. D. Hyndman, "Theater television
committee report," Jour. SMPTE,
56: 124-125, Jan. 1951.

23. "Theater television and the FCC,"
ibid., 57: 78-80, July 1951.

24. "Theater carpeting manuals avail-
able," ibid., 54: 646-647, May 1950.

F. T. Bowditch: Engineering Activities

177

Explosive Argon Flashlamp

By G. H. WINNING and H. E. EDGERTON

Oscillo graphic measurements of the light output from argon explosive flash-
lamps show that the flash duration is about 1 jusec for a 0.5-cm thickness of argon
over the end of a cone of cast pentolite 2 in. in diameter. The peak light out-
put is about 200 million cp, and the total output about 200 cp sees. Photographs
of the argon lamps were made with a magnetooptic shutter having an effective
exposure of about 1 pisec to show the space origin of the light.

HE PHOTOGRAPHY of detonations by
means of an ordinary single-exposure
camera has been difficult to accomplish
for two reasons. First, either the light
from the detonation of high-temperature
explosives is so actinic as to fog the film;
or the light from the detonation of rel-
atively low-temperature explosives such
as those of the permissible, coal-mining
type, for example, is insufficient to affect
the film in the brief exposure time re-
quired to stop the motion. Second,
although conventional short-flash elec-
tronic flashlamps might be considered
for some purposes, their use is expensive
because the lamp is destroyed by the
explosion.

The second difficulty may be over-
come, for problems where the subject is
not excessively large, by the use of

Presented on April 23, 1952, at the Society's
Convention, at Chicago, 111., by C. H.
Winning, E. I. duPont de Nemours &
Company, Explosives Dept., Eastern Labo-
ratory, Gibbstown, N.J., and H. E.
Edgerton, Massachusetts Institute of Tech-
nology, Electrical Dept., Cambridge 39,
Mass.

another explosive to produce light at the
proper time. A relatively inexpensive,
expendable, flash-producing, explosive-
activated lamp is described here. The
objects of this paper are, first, to present
oscillographic measurements of the light
output from an argon-filled explosive
flashlamp and, second, to present se-
quence photographs of the exploding
lamp itself for correlation with the
oscillograms.

Successful photography of self-lumi-
nous subjects may be accomplished by
the use of Kerr cells, Faraday-effect
shutters, and by image-converter tubes.
The series of photographs published here
of the explosive argon flashlamp during
explosion were taken with the Rapa-
tronic shutter (Faraday magnetooptic
type).

Argon Flashlamp

In 1937 Michel-Levy and Muraour
published a series of pictures which
illustrated that rapidly occurring events,
such as the deformation of a lead block
by an explosive, could be photographed
at desired instants during the process
through proper use of the short, intense

178

September 1952 Journal of the SMPTE Vol. 59

luminosity of the shock wave generated
in argon gas by a small amount of a
brisant explosive.1

Shock-wave flashes of about 4- to 20-
/xsec (4 to 20 X 10~6 sec) duration and
300-600 million cp intensity were pro-
duced by detonating 0.4-5.0 cm3 of a
brisant explosive (tetranitromethane plus
toluene) in the end of a small, grooved
brass cylinder, above which was a cello-
phane tube filled with the argon. The
cellophane tube and the brass cylinder
had the same diameters, namely 8 mm or
more. The vertical cellophane cylinder
of argon traversed by the luminous shock
wave had a height of about 8 cm.2*3
Apparently the selected materials and
dimensions favored the production of
brief, intense luminosity.

Later investigators who employed the
argon flashlamp in photographing vari-
ous explosive phenomena used modified
forms of the lamp. Shepherd reported
use of a lamp consisting of approximately
^ oz of pressed tetryl inside a cardboard
cylinder 2 in. in diameter. The end of
the cylinder had a cellophane window.4
The duration of luminosity of the flash-
lamp was estimated to be 2-4 /*sec. The
pictures, which were taken by either
front or back lighting (silhouette), illus-
trated that the light from the argon
flashlamp, even though spread over the
expanse of the subject at different
selected stages in the explosion process,
was much more brilliant than the hot gas
from the permissible-type explosives.
U.S. military investigations during World
War II included photographic studies of
underwater explosions, which required
the development of lamps suitable for
(1) the illumination of gas bubbles from
explosions at different depths and (2) the
illumination of relatively small, high-
velocity, demolition explosives detonat-
ing relatively near the camera. In order
to obtain flashes of high intensity and
short duration, attention was given to
both the surface area of the charge
generating the shock wave at a given in-
stant and to the thickness of the argon

layer traversed by the shock wave.
Both spherical and conical cast pentolite
charges were employed.6 It was found
that both the duration and the intensity
of the illumination increased with the
thickness and the area of the argon gas
layer, but details about the methods and
results have not been published in the
open literature.

The present paper includes micro-
second photographs and oscillograph re-
productions which show the character-
istics of the brief flash of intense light de-
veloped by a conical explosive charge in
an experimental type of flashlamp used
at Eastern Laboratory.

Experimental

Photographs of the argon flashlamp
were made with a one-microsecond
Rapatronic shutter.6 The shutter is
triggered by the light from the explosion
by means of a photoelectric cell (RCA
929) and an adjustable time-delay cir-
cuit.

The Rapatronic shutter consists of
crossed polarizers between which is a
slug of extra-dense flint glass as shown in
Fig. 3. The shutter is opened by causing
the plane of polarization to rotate in the
glass (Faraday effect) by an axial mag-
netic field.

The 1-jusec exposure is produced when
a 24-kv, 0.125-/xf capacitor is discharged
through a triggered air gap into a nine-
turn coil around a slug of extra-dense
flint glass 1 in. in diameter. The plane
of polarization of the light passing
through the glass is rotated by the mag-
netic field. A doublet camera lens of
about 6-in. focal length was used in
front of the Rapatronic shutter. Visual
focusing was accomplished by rotating
one of the polarizers that normally are
crossed on opposite ends of the flint glass.

The light-time oscillographic trace
was displayed on a Du Mont Type 256A
ranging oscillograph, and a photograph
was made to record the transient. Light
from the argon explosion was allowed to
fall on the cathode of an RCA Type 929

Winning and Edgerton: Explosive Argon Flashlamp

179

Fig. 1. Explosion of argon flash lamp.

A. Lamp with watch glass 0.5 cm ahead of conical pentolite charge.
"Primacord" initiator and argon gas line are at rear.

B. Frontal lamp flash about 0.5 jtsec after attaining maximum intensity.

C. Condition about 3 /zsec after maximum flash.

D. Condition about 7 jusec after maximum flash.

phototube (S4 cathode) which had a
1000-ohm load resistor and a plate sup-
ply of 2000 v. The high plate voltage
was necessary to assure that current and
light were proportional at the large
values of current. The time constant of
the output circuit was estimated to be
less than 0.1 j*sec.

Calibration of light deflection was
made by the use of a General Radio
Strobolume which produces about 10
million peak beam candlepower.

The explosive flashlamp (Fig. 1A),
whose performance is reported in this

paper, consisted of a 2-oz conical, cast
pentolite (50-50 PETN and TNT)
charge within a 2.5-in. diameter glass
tube containing argon. The front of the
conical charge (contained in a glass
funnel) was curved to conform with the
curvature of the watch glass sealed over
the front of the lamp. The desired 0.5-,
1 - or 2-cm spacing for argon between the
explosive charge and the watch glass was
fixed by using a spacer made from a thin
gelatin capsule. The pentolite charge
was initiated at the rear apex of the cone
by means of the "Primacord" detonating

180

September 1952 Journal of the SMPTE Vol. 59

U SEC. - TIME

Fig. 2. Luminosity-time curves for argon flashlamps.

Symbol

Thickness of argon

layer at front of

lamp, cm

0.5
1.0
2.0

fuse which entered the charge through
the stem of the funnel. The air in the
lamp was flushed out with argon ad-
mitted through a tube at the rear of the
lamp.

Microsecond Photographs

Figure IB shows a picture of the argon
flashlamp about 0.5 /xsec after the
maximum intensity of the flash. It may
be observed that the luminosity is slightly
more intense, and perhaps near the
maximum, around the circumference of
the face, that is, in the narrow outer
region slightly removed from the im-

mediate frontal effect of the explosive.
(The front of the lamp had an inside
diameter about 0.5 in. greater than that
of the explosive charge.) Also evident
in the picture is what appears to be a
small hole at the center and front of the
charge where a 0.5-cm spacer was lo-
cated. (This spacer was made of cork
rather than gelatin.) No light is evident
lateral to the direction of propagation of
the detonation at the instant of this
photograph.

Figures 1C and ID are pictures of the
lamp taken about 3 and 7 /xsec, respec-
tively, after the highly actinic flash from
the front. In the approximate exposure
time of 1 ptsec, the hot explosive gases are
not sufficiently actinic to appear lumi-
nous; and accordingly, the gas cloud
pouring out of the front appears black.
As the explosion gas spreads out laterally,
it obscures the lateral actinic flash in the

Winning and Edgerton: Explosive Argon Flashlamp

181

-DENSE FLINT GLASS
-P2

FILM

I MICROSECOND
MAGNETO OPTIC
SHUTTER

PHOTOCELL TRIP

Fig. 3. Rapatronic magnetooptic camera arrangement used to photograph
the argon flashlamp.

argon, that is, at the rear portion of the
lamp and around the apex of the conical
charge.

Figure 2 is a scaled reproduction of the
oscillograms obtained on explosive flash-
lamps having frontal argon atmospheres
0.5, 1 and 2 cm thick. No corrections
have been made for adjustment to refer-
ence oscillograms obtained with a
standard 1 0 million cp lamp prior to each
experimental shot. With 0.5 cm of
argon the major portion of the flash was
over in 1 jusec or less. The exact shape
of the increasing and decreasing lumin-
osity curve could not be ascertained on
the recorded scale. The average of the
three records for 0.5 cm of argon, by
comparison with records of a standard 1 0
million cp lamp, reveals a peak intensity
of about 225 million cp. The flash-
lamps with 1 cm of argon had a duration
of 2 /isec for the maximum luminosity,
and the initial rate of increase in lumin-
osity appeared to be approximately that
for the 0.5-cm argon layer, but there was
a slightly higher maximum. The maxi-
mum intensity was 250 million cp. With
2 cm of argon the first and major portion
of the luminosity increase was practically
as rapid as for the two preceding spac-
ings; however, the duration of the
maximum luminosity was about 4 /usec,
and the peak intensity was about 300
million cp. The uncertainty of the refer-
ence standard for this record makes the

maximum a littie more uncertain than
for the others. A small, trailing lumin-
osity was evident about 1 or 2 jusec after
the main flash in all cases. This phe-
nomenon could be attributed to a lagging
luminosity at the circumference, as
indicated in Fig. IB.

Discussion of Results

The oscillograms indicate that the
duration of the main flash from the argon
flashlamp, as measured by the writers,
is about 2 ^isec for each centimeter of
thickness of the argon layer. The
maximum intensity is developed after
one-half to three-quarters of this time
interval has elapsed. The measure-
ments cover argon layers 0.5 to 2 cm
thick. The time for development of the
maximum intensity probably is related
to the time required for the shock wave
in the argon to reach the front of the
lamp.

The average peak intrinsic brilliancy
of the sheet of light-radiating argon gas
is calculated by dividing the peak light
(225 million cp) by the area (33 sq cm).
This value is 6.8 million cp/square
centimeter. Flash bombs with larger
output would supposedly be of larger
argon area. Some care might be re-
quired to initiate the flash of all portions
of the sheet of gas at the same instant.

The duration and light-intensity data
of Muraour et al.2>3 closely resemble

182

September 1952 Journal of the SMPTE Vol. 59

those presented here, but these investi-
gators did not determine the time-
intensity curve. They calculated the
average intensity from the measured
photoactinic effect on film (by compari-
son with a standard) and from knowledge
of the duration determined either by
photographing rapidly moving objects of
known velocity, or by use of rotating-
drum-camera pictures.

Continuing experimental studies of
explosive flashlamps should consider
other rare gases such as krypton, neon
and xenon as well as other explosives for
creating the shock wave. Since xenon
is preferred to argon in electronic flash-
lamps, it is assumed that it might be
better in explosive lamps.

Photography With Argon Flashlamp

Consider now the photographic use of
the l-jtisec argon flashbulb as described.
The following relationship is often useful
in arriving at a preliminary set of ex-
posure conditions:

DA =

where

D = lamp-to-subject distance in feet

A = aperture of lens

Q, = total light output in lumen-
seconds

M = reflector factor

K = a constant which depends upon
the type of film used and the processing.

For the argon flashlamp without a re-
flector, M = 1 and Q, = 10 X cp-sec
= 2000 Im-sec (approximately). K is
about 0.25 for fast film. Now if A is
selected to be about//4.5, then the lamp-
to-subject distance, D, can be calculated.
D equals about 5 ft.

This result must be used with judg-
ment, depending upon the reflectivity of
the subject that is being photographed.
Often a sheet of white cardboard imme-

diately back of the subject is very useful in
giving a silhouette of darker portions of
the subject.

The contrast of photographs is usually
low when they are taken with blue light
of short exposure time. This lack of
contrast can be corrected by a longer de-
velopment time or the use of a more
vigorous developer.

References

1. A. Michel-Levy and H. Muraour,
"Photographs of phenomena accom-
panying explosion of a brisant explo-
sive," Compt. rend., 204: 576-579, 1937.

2. H. Muraour, "Shock waves and deton-
ation luminosities," Chimie & Industrie,
47: 3-15, 1942.

3. H. Muraour, A. Michel-Levy and E.
Vassy, "A flash source for photographic
purposes," Rev. optique, 20: 161-164,
1942.

4. Safety in Mines Research Board, 25th
Annual Report, 1946, H. M. Stationery
Office, London, 1947, pp. 29-31.

W. C. F. Shepherd, "Coal mining ex-
plosives; present day research of the
Safety in Mines Research and Testing
Branch, Ministry of Fuel and Power," in
Proceedings; Fifth International Conference
of Directors of Mine Safety Research, Bull.
489, U.S. Bureau of Mines, U.S.
Government Printing Office, Washing-
ton, D.C., 1950.

5. J. E. Eldridge, P. M. Fye and R. W. S.
Spitzer, "Photography of underwater
explosions," Office of Scientific Re-
search and Development, Report 6246,
1947 (P.B. 96667, Office of Technical
Services, U.S. Department of Com-
merce, Washington, D.C., 93 pp.)
See also: Paul M. Fye, "The high-speed
photography of underwater explosions,"
Jour. SMPTE, 55: 414-424, Oct. 1950.

6. H. E. Edgerton and C. W. Wyckoff,
"A rapid-action shutter with no moving
parts," Jour. SMPTE, 56: 398-406,
Apr. 1951.

7. H. E. Edgerton, "Light-meter uses with
electronic flash," PSA Jour., Part II,
Photographic Science and Technique, 16:
6-10, Jan. 1950.

Winning and Edgerton: Explosive Argon Flashlamp

183

Integrating-Type
Color Densitometer

By FRANK P. HERRNFELD

This color densitometer is for making diffuse density measurements in the
blue, green and red, as well as visual bands. This densitometer utilizes an
integrating bar for gathering the light, therewith greatly increasing the
sensitivity as compared to other methods presently used.

JL HE REQUIREMENTS for a color densi-
tometer are very similar to those of a
black-and-white unit. Enumerated ac-
cording to importance, they are:

1. reproducibility of readings,

2. simplicity of operation,

3. sufficient range and flexibility,

4. accuracy, and

5. electrical calibration.

Reproducibility of reading was ac-
tually the hardest part of our design
problem. We found that a stable
amplifier alone was not the answer.
It calls for rugged mechanical construc-
tion, the selection of the proper photo-
electric cell, stable optical filters, a
color-corrected optical system, and many
small features too numerous to mention.
When the desired stability was reached,
the unit was finished.

Presented on April 24, 1952, at the Society's
Convention at Chicago, 111., by Frank P.
Herrnfeld, Frank Herrnfeld Engineering
Corp., 5880 Blackwelder St., Culver City,
Calif.

Figure 1 shows the optical schematic
of the instrument. As light source we
use a General Electric 4AT8-34 lamp
rated at 8.5 v 4.0 amp. In operation
the lamp burns at 7.5 v, has an approxi-
mate color temperature of 3000 K, and
a life expectancy of 500 hr. In stand-
by condition, the voltage is reduced to
5.0 v. A special socket insures proper
electrical contact and placement on the
optical axis. Both vertical and hori-
zontal adjustments of the lamp socket
are provided.

The condenser lens has full achromatic
correction and focuses the filament of
the lamp onto an aperture. An inter-
rupter wheel and an infrared absorbing
filter are located between the condenser
lens and the aperture. The interrupter
wheel, driven by a 3600-rpm synchro-
nous motor, modulates the light beam
at the rate of 360 cycles/sec, making
the use of a stable a-c amplifier possible.

The infrared filter is a Corning No.
9780 2^-mm thick glass and is always in
the light beam. It has the dual purpose
of (a) reducing the heat rays reaching

184

September 1952 Journal of the SMPTE Vol. 59

OBJECTIVE LENS

FILM PLANE

INTEGRATING BAR
\°J RE.CELL
Fig. 1. Optical schematic of the integrating-type color densitometer.

the photosensitive surface of the photo-
electric cell in the red and visual setting
of the densitometer and (b) eliminating
undesirable near-infrared light reaching
the photoelectric cell passed by all blue
and green filters.

Either of two apertures can be used
for making density measurements. One
is a round one, illuminating a circle of
about -^ in. in diameter at the film
plane; the other is rectangular, illumi-
nating a 0.015 by 0.125 in. area. The
round aperture is meant for general
work and the rectangular one for the
measurement of variable-area sound
track.

A fully achromatic corrected objective
lens focuses the aperture onto the film
to be measured. The color and visual
filters and a front-surfaced mirror are
located between the aperture and the
objective lens.

Four filters are mounted in a wheel.
A neutral density is mounted with each
filter to bring the photoelectric cell
output to the same value. This mini-
mizes zero adjustment when going from
one color band to another. An inte-
grating bar collects the light passing

through the film and delivers it to the
photoelectric cell.

In checking all available commercial
photoelectric cells, we found only two
that lend themselves readily to the
measurement of density, namely the
RCA 1P42 and 929, or the equivalent
in other makes.

We found that the 1P42 had an un-
desirable lag and color fatigue in the
blue and green bands with the amount
of light necessary to measure to a color
density of 4.0. This can be partially
overcome by raising the anode voltage
above the ionization potential (18 v).

Raising the anode voltage sufficiently
to overcome the fatigue problem raises
two others: (1) If any trace of gas is
left in the photoelectric cell, the cell
will become nonlinear in the low density
range when the greatest amount of light
is present. (2) It will raise the dark
current which means more noise, re-
ducing the small margin between signal
to noise in tffe high density range.

The 929 photoelectric cell has a
greater output for a given light input,
and does not seem to suffer from the
above-mentioned shortcomings of the

Frank P. Herrnfeld: Color Densitometer

185

1P42, but the photosensitive surface is
too far from the film to make the tube
a good receiver. Means to gather all
the light, coming through the sample
tested have to be provided. This is
important when measuring the density
of negatives, as all silver images and cyan
dyes show a greater density when meas-
ured in a spectral system.

We know of only three methods to
measure true diffuse density:

1. placing the sample to be measured
directly in contact with the photosensi-
tive circuit,

2. utilizing a sphere, up to now con-
sidered the standard in the motion pic-
ture industry, and

3. utilizing an integrating bar.

The first method, theoretically the
most simple, is nearly impossible in
actual practice. The second method,
excellent in black-and-white measure-
ments, introduces too much loss into the
system. Depending upon the method
of coating and the size of the sphere,
a loss of light equivalent to inserting a
density between 1.3 and 1.5 is the
minimum obtainable in practice. Add-
ing this loss to the insertion loss of the
optical filters will restrict any instrument
using a design similar to ours to a maxi-
mum density range of 3.0.

The third method, the integrating
bar with a diffusing surface toward the
film to be measured, retains all the ad-
vantages of a sphere. It introduces a
loss of light equivalent to inserting a
density of 0.6, making diffuse color
density measurements of 4.0 possible.

Table I shows the measurements
obtained from three common sound
track emulsions when measured with a
sphere, integrating bar and spectral
type of instrument. For comparison
they were measured with a sphere-type
densitometer having a visual-type color
characteristic and the visual filter on
our Model 1503A with and without
the integrating bar.

The differences between readings of
the sphere type and 1503A with the
integrating bar are due to difference in
spectral sensitivity of the two instru-
ments.

Figure 2 shows the spectral distribu-
tion of the light source and the visual
filter with this light source compared
to an average eye characteristic.

Figure 3 shows the spectral distribu-
tion of the three combination color
filters with the light source shown in
Fig. 2.

As mentioned before, the Corning
No. 9780 infrared absorbing filter is

Table I. Comparison Test of Three Common Sound-Track Emulsions
(using Pathe 2B Sensitometer).

E.K. 5373, 4-min dev. DuPont 836, 5-min dev. DuPont 831, 9-min dcv.

Step

RA- RA- RA-

1100B 1503A 1503A-S 1100B 1503A 1503A-S 1100B 1503A 1503A-S

0.04

0.03

0.05

0.07

0.09

0.13

0.06

0.05

0.08

0.06

0.09

0.11

0.12

0.15

0.11

0.09

0.16

0.12

0.10

0.19

0.18

0.19

0.26

0.19

0.17

0.29

0.20

0.17

0.31

0.40

0.44

0.56

0.33

0.28

0.48

0.33

0.29

0.50

1.00

1.08

1.37

0.49

0.46

0.71

0.53

0.48

0.75

2.05

2.16

2.63

0.69

0.66

0.95

0.77

0.71

1.06

3.18

3.28

3.75

0.90

0.88

1.21

1.07

1.00

1.43

3.87

3.97

4.+

1.12

1.10

•l.47

1.39

1.33

1.80

1.31

1.67

1.71

1.67

2.13

1.45

1 .47

1.81

1.94

1.95

2.38

Gamma

0.69

0.88

0.96

1.17

3.66

4.68

1.27

1.22

1.28

186

September 1952 Journal of the SMPTE Vol. 59

-1.0

!-2.0

500 MILL! MICRONS 600 700

Fig. 2. Response of light source visual filter and eye. A: tungsten
2780 K+Corning 9780 +929 photoelectric cell; B: light source + Corning
3389; C: average human eye.

40O

400 500 VIILLI MICRONS 600 700

Fig. 3. Response of color filters. A: light source +Corning 3389+5113; B: light
source -fCorning 3486+4010; C: light source +Corning 2408.

Frank P. Herrnfeld: Color Densitometer

187

Fig. 4. Amplifier schematic.

Ml — indicating instrument
PI — zero density adjustment
P2 — range selector
P3 — 1.0 density adjustment
VI — 929 photoelectric cell

V2 — 12SF5 amplifier

V3 — 12SJ7 amplifier

V4 — 12SJ7 amplifier

V5 — 12H6 rectifier

V6 — 12SL7 vacuum-tube voltmeter

always in the light beam. The visual,
blue, green and red filters are located
in an indexed color wheel. The blue
filter consists of two Corning glasses,
Nos. 5113 and 3389; the green filter
of two Corning glasses, Nos. 4010 and
3486; and the red of one Corning glass
No. 2408.

The minimum bandwidth of the sys-
tem is fixed by the filters having the
least amount of output in conjunction
with the photoelectric cell used. In this
case, the Corning glasses Nos. 9780 and
2408, with the 929 photoelectric cell
and the lamp burning at 3000 K de-

termine the bandwidth. The green and
blue filters are chosen to give a similar
characteristic having greatest transmis-
sion at 540 and 445 rmz respectively.
Corning glasses were chosen for their
greater permanence.

Figure 4 shows the electrical schematic
of the amplifier. The zero adjustment
is in the cathode of V2, the first amplifier
tube, and has a range of about 8 db,
equivalent to a density change of 0.40.
P2 is a 20 db per step pad, having a
total range of 100 db, giving ranges of
0 to 1, 1 to 2, 2 to 3, and 3 to 4. Also
included is the 1.0 calibration position.

-20

-30

100 1000

FREQUENCY IN CYCLES PER SECOND
Fig. 5. Frequency response of amplifier.

10000

188

September 1952 Journal of the SMPTE Vol. 59

V3 and V4 are a stabilized amplifier of
constant gain. V5 and V6 comprise a
balanced vacuum-tube voltmeter. Line
voltage changes are balanced out and
will not affect the readings. This does
not mean that the instrument should
be used without a voltage regulating
transformer, as changes in the supply
for the light source will greatly affect
the stability of reading.

The indicating meter Ml has special
pole pieces to give the instrument an
approximately linear scale with logarith-
mic input over a 10 to 1 range. The
circuit is arranged in such a manner
that with an increase in current, the coil
of the meter moves into a magnetic
field of lesser density. This arrange-
ment prevents a runaway condition and
makes for a better instrument. P3 is
the 1.0 calibrating adjustment.

Figure 5 shows the frequency response
of the amplifier section V3 and V4.
This characteristic is caused by the
tuned circuit in the cathode circuit of
V3. The peak transmission corresponds
to the frequency of the interrupter
wheel in the light beam and eliminates

to a great extent errors in reading due
to stray light reaching the photoelectric
cell.

The filaments of all tubes are fed from
a direct current source. The anode
voltages on the photoelectric cell and of
V2 are sufficiently low to eliminate any
noise and nonlinearity due to gas present
in the tubes.

Figure 6 shows the finished instru-
ment. The unit is made to fit into a
table or desk with the power unit to be
mounted out of the way of the operator.
All controls are located on top of the
panel.

Upon completion, the unit was tested
with several different lamps as light
source. Reproducibility of readings
was checked over a four-week period.
The first two weeks the unit was checked
each working day by the hour on the
hour, allowing a 5-min warm-up period
before making a reading. The instru-
ment was shut off after each test. The
latter two weeks the instrument was left
on continuously.

The readings thus obtained were in
all instances within 0.02 of the original

Fig. 6. Model 1503 A color densitometer.
Frank Pt Herrnfeld; Color Densitometer

189

measurement. Aging or changing of
the lamp had no influence on the
readings.

The different density ranges and
calibrations are selected by five push
buttons plainly marked in front of the
meter case. The film strip is held in a
step-calibrated carriage, allowing easy
selection of different tablet steps. After
a 15-min warm-up period, recalibration
is seldom necessary.

The maximum range of the instru-
ment is sufficient for all measurements
encountered in the motion picture
industry. Selection of the proper filter
is simple and sure. All readings taken
are diffuse readings and no change of
location of the photoelectric cell is
necessary.

The absolute accuracy of reading,
compared to a sphere-type and visual-

type instrument, is sufficiently close for
all purposes for which the instrument
may be used. A 20-db signal-to-noise
ratio on its highest reading, at a density
of 4.2, guarantees accuracy over the
complete range. The bandwidth of
each of the three color filters is suffi-
ciently narrow, and the suppression of
all unwanted radiation sufficient to give
an insertion loss of more than the
equivalent of a density of 7.0 to white
light when any two of the three filters
are placed into the light beam at the
same time.

The instrument is calibrated elec-
trically. The accuracy thus obtained
is only a function of how much care
has been taken in doing it.

Several of these instruments are now
in commercial service and have given
consistent results.

190

September 1952 Journal of the SMPTE Vol. 59

Transmission Color
in Camera Lenses

By PHILIP T. SCHARF

The color contribution of a lens has been defined in terms of its transmittance
density at 400 and 700 mM. It is proposed that the difference in the densities
at these two wavelengths be held to 0.05 ± 03 for motion picture camera lenses;
0.05 d= .05 for other camera lenses. To prevent the curve from being too highly
inflected between these two points an additional requirement is that the mini-
mum density between 400 and 700 m/x differ from the density at 700 m^t by no
more than 0.04 density units. It has been found convenient to describe
quantitatively the glass absorption by a term called "color index." A simple
method of determining the combined effect of glass absorption and surface
coating is outlined.

-L HERE HAS BEEN considerable interest
in recent years in the subject of camera
lens transmission. Prior to the advent
of antireflecting coatings it was not un-
heard of to have light losses amounting
to as much as 50%. With present-day
coated lenses, however, losses greater
than 10% are seldom encountered. In
terms of lens aperture this means that
the loss of light with a coated lens does
not exceed J of a stop. While there may
still be reason for occasionally investi-
gating the overall light loss of a coated
lens, other variables in the photographic
process will generally mask this ^ of a
stop. On the other hand, the color of
the light transmitted by camera lenses

A contribution submitted June 17, 1952,
by Philip T. Scharf, Process Development
Dept., Hawk-Eye Works, Eastman Kodak
Co., Rochester, N.Y.

has caused much less interest, but in
present-day practices it is probably more
important than the overall white light
transmittance. The increased interest
in color photography is responsible for
the importance of this color factor.
Interchangeable lenses on cine cameras
have made it possible for the photog-
rapher to perform a very critical test for
the uniformity of color in his lenses. In
this case the same scene, the same film,
and the same processing variables are
maintained while only the lens is varied.
This means that if the same exposure is
used, the only variable is the color of the
lens. We wish to center our attention on
this subject of color variations occurring
in lenses, and to investigate methods of
minimizing this variation.

There are two distinct factors con-
tributing to the color of a lens. The
first is the color of the glass itself. This

September 1952 Journal of the SMPTE Vol. 59

191

0.10

Blue coating

Glass absorption
Simple lens Complex lens

Magenta
coating

400

700

500 600

Wavelength in m/^

Fig. 1. Transmittance losses from glass absorption and coated surface reflection.

color, generally yellowish, is caused by
the ultraviolet absorption band of glass.
Modern experiments have proven that
in most optical glasses the visual color is
a function of impurities present in the
raw materials. At some future date,
production quantities of all the common
optical glasses may be available free of
color. Until then we must learn how to
use existing glasses. We have made a
fairly extensive study of all the commonly
used glasses from many sources. Two
important findings that have come from
this study are that there is a considerable
difference between manufacturers and
that the sources supplying color-free
glasses appear to be able to maintain
their quality. These findings have en-
abled us to put a certain degree of con-
trol over this first source of color in a
lens.

It is generally recognized that the
antireflecting coatings impart a degree of
color to the transmitted light. If we
observe the light reflected from different
thicknesses of these coating films we see
that the thinner films are yellowish or am-
ber, the thicker ones bluish, with magenta

films lying in between. The yellow reflec-
tion means that less blue light is reflected
than red or green which in turn can be
interpreted as meaning that more blue
light is transmitted. Likewise the ma-
genta coating means more green light
is transmitted and the blue coating
means more yellow light is transmitted.
Since coatings do transmit light selec-
tively we have here the second con-
tributing source of color in the lens. An
advantage can obviously be gained if
we can get these two factors to cancel one
another. Figure 1 is a plot of the two
color-contributing factors in terms of
wavelength and transmittance density.
It can be seen that the curve shapes are
essentially different so that complete
cancellation cannot be hoped for, but a
good approximation is possible. Simple
lenses having little glass absorption will
need less color compensation from the
coatings than the more complex lenses.

The complete color specification for a
lens is given by its spectrophotometric
curve as shown in Fig. 2. However, a
single quantity would be convenient to
use in expressing the varying degrees of

192

September 1952 Journal of the SMPTE Vol. 59

0.20

0.10

400 500 600 700

Wavelength in m/i

Fig. 2. Spectral transmittance of coated lenses.

color. It was decided that since we are
dealing with more or less similar curves
the difference in characteristics at two
points of the spectrum would suffice to
specify the color. From the standpoint
of measurement accuracy, wavelengths
should be chosen to give as large a den-
sity difference as possible. On the other
hand the limits of sensitivity of color
films are a consideration. As a com-
promise 400 and 700 imt were chosen.
Since transmittance densities are addi-
tive we shall speak of the color contribu-
tion in terms of the transmittance density
difference at 400 and 700 mju. That is,
Z)4oo— Z>7oo equals the color contribution.

Having defined this quantity it will be
convenient to evaluate the two sources of
color in terms of this quantity. To this
end we have defined a term known as
"color index" for a description of the
color of a piece of glass.

If t is the glass thickness in millimeters,

Color Index =

~ Aoo

The glasses most free of color have
values from 0 to 0.0005. The worst
glasses for color have indices of 0.0300.
When using color index as a manufac-
turing tolerance it has been convenient to
multiply by a factor of 104 to give integral
values 0-300.

To compute the glass contribution we
have merely to multiply the lens thick-
nesses in millimeters by the color index
of the glass from which the lenses were
made. The use of densities instead of
per cent transmittance permits adding
the values from each lens element. This
gives us a simple method of determining
quantitatively the effect of the glass
absorption, and now we turn to the coat-
ing problem.

The color arising from the film coating
is a function of three variables — the
index of the glass, the number of coated
surfaces, and the thickness of the coated
film. The first two are fixed in the de-
sign of a lens so that we have only the
last variable left for control. The trans-

Philip T. Scharf: Transmission Color in Lenses

193

mittance through a single coated surface
may be plotted in terms of transmittance
density versus wavelength for varying
film thicknesses. From these curves we
can tabulate our density difference
Z)4oo — D-iQQ for each of several film thick-
nesses. If we do this for glass indices
from 1.50 to 1.90, we find that for a given
film thickness the color contribution
jD40o — AGO plotted against glass index
gives very nearly a linear relation. This
provides us with an important simplifica-
tion, for, if we have a lens consisting of
glasses of differing indices, rather than
compute the effect for each index we can
use a "weighted index" for the lens as a
whole. This "weighted index" is de-
termined by using for each lens element
its refractive index times zero, one or
two, depending upon the number of its
coated surfaces. These weighted values
are added together for the entire lens
and divided by the sum of the weight-
ings, that is, the total number of coated
surfaces. We now use a table having
as entries the film thickness and the
weighted index. The body of the table
consists of the color contributions from
the coated glass surface. We have found
it convenient to have a table for four,
six and eight coated surfaces. The dis-
persion of glass has been taken into ac-
count in setting up the tables, although
this is a secondary effect.

The color contribution arising from
glass absorption is always a positive
quantity, i.e., the Z>4oo — Aoo is always
greater than zero since the glass trans-
mittance density in the blue region is
greater than in the red. The contribu-
tion from the coating, however, takes on
negative values as well as positive values
and this is what enables us to control the
transmission color of the lens. A coating
having its minimum reflection at about
500 mfj. has a zero value for the term
Z>40o — D7QQ regardless of glass index.

Thinner coatings have negative values,
thicker ones positive values. There is of
course a limited amount of control
offered by the coating; the higher the
glass indices and the more coated sur-
faces, the greater the control. For ex-
ample: a lens having a weighted index
of 1.70 and eight coated surfaces can
have a negative color contribution of as
much as 0.11 while the maximum nega-
tive contribution from a lens having four
coated surfaces and a weighted index of
1.55 is 0.03.

It is now a simple matter to determine
the combined effect of glass and coating
on the transmission color of a lens. But
we are still without a limiting value for
this color. It was felt for the most
critical lenses, interchangeable cine
lenses, the departure from neutrality
should not exceed the amount introduced
by the lightest filter that may be used.
In the Kodak Wratten series of Light
Balancing Filters the lightest is the No. 81 .
It has a value for Z)4oo — -Dyoo of 0.08.
It was found that for the simplest cine
lenses 0.02 represented the minimum
color contribution. This range 0.02 to
0.08 was therefore taken as a reasonable
range of color contribution values for
cine lenses. Other camera lenses being
less critical for color could have the
range 0.0 to 0.10. To avoid any possi-
bility of the spectral curves becoming too
highly inflected between 400 and 700
rm«, it is suggested that the expression
Z)70o — Aninimum have a maximum value
of 0.04, that is, the density at 700 m/i
must be within 0.04 of the minimum
density wherever it is.

There will of course be camera lenses
which cannot be made to meet these
color specifications. Large aerial lenses
are examples, but in such cases we do not
ordinarily have rigid requirements for
neutral transmission.

194

September 1952 Journal of the SMPTE Vol. 59

Cameo Film Production Technique

By CHARLES F. HOBAN and JAMES A. MOSES

Educational and psychological principles applied by the Signal Corps in
experimental film designed to increase training effectiveness and to cut time
and cost of production are presented. Also described are story treatment,
studio techniques, and preproduction analysis and planning that are involved
in these productions. Results are reported of the evaluation study of film
effectiveness and audience reaction to scenario treatment.

N«

ONTHEATRICAL film producers are
under increasing pressure to do two
things which appear contradictory and
irreconcilable. There is the demand
that training, information and public-
relations films be produced more rapidly
and more economically. At the same
time, there is a demand that the effec-
tiveness of films be increased. Under
conventional production procedures,
films cost too much and take too long to
produce. When produced, films fre-
quently do not accomplish their purpose
as effectively as sponsors hope and have a
right to expect. To film producers who
equate "film quality" with film effec-
tiveness, it seems impossible to make
better films and, at the same time, reduce
the time and cost of production.

In this paper we will describe some
applications of educational and psycho-
logical principles of film influence to

Presented on April 22, 1952, at the Soci-
ety's Convention at Chicago, 111., by Lt.
Col. Charles F. Hoban and James A.
Moses, Army Pictorial Service Div., Of-
fice of the Chief Signal Officer, Dept. of
the Army, Washington 25, B.C.

story treatment and studio methods be-
ing developed by the Signal Corps to
improve training effectiveness and reduce
time and cost of production. Use of
these procedures will be illustrated in the
experimentally produced Army training
film, TF 11-1752 How to Operate the
Army 16mm Sound Projector Set. There is
some reason to believe that the basic
educational principles applied to the film
on operation of the projector set are not
necessarily limited in application to this
particular film or to training films of the
"nuts and bolts" type. However, we
are not concerned with a specific tech-
nique used in the experiment. It just
happened that the particular production
technique fitted the subject and accom-
plished the desired results. Under no
circumstances should the production
technique used in this film be construed
as a "blueprint" for film productions in
general.

Two sources of inspiration for im-
proved film production procedures and
techniques are currently available. For
one thing, the possibility of low-cost, rapid
program production has been explored
extensively by commercial television and

September 1952 Journal of the SMPTE Vol. 59

195

by the Navy's Special Devices Center at
Port Washington, N.Y. The affinity of
television to radio, by way of establish-
ment of television studios and networks
in association with radio studios and net-
works, brought into television a group of
artists, craftsmen and technicians not too
familiar with motion picture production
and motion picture studio practice.
Partly because of studio and small-screen
limitations, and partly because of fresh
talent in the television industry, tele-
vision has changed the format of video
presentation and revived many tech-
niques successfully used in the past in
military training and other nontheatrical
films.

The second influence on film production
methods and techniques, particularly in
training and informational films, is the
growing body of research data on factors
which increase the instructional effec-

tiveness of motion pictures. On the
whole, this research has tended to verify
and emphasize the applicability to mo-
tion pictures of well-known instructional
procedures, and to demonstrate that the
training and informational effectiveness
of films is measurably increased when
instructional procedures are incorporated
into film production.

This emphasis on instructional tech-
niques in training and informational films
is almost as unwelcome to the profes-
sional film producer as is the emphasis
of the television producer on production
shortcuts and simplified background and
sets. Teachers are, as J. E. Morpurgo
says in The Impact of America on European
Culture, "the depressed class in America's
predominantly commercial society."
Instruction techniques are associated
with teachers. Submergence of teachers
in the American value system submerges

Fig. 1. ". . . occasionally Jim steps out of his role, and for a moment, is the
master of both the machine and of the practical aspects of the theory."

196

September 1952 Journal of the SMPTE Vol. 59

the prestige of instructional techniques
identified with teachers. However, the
relationship of scientific research in
nuclear physics to the engineering de-
velopment of the atomic bomb had the
indirect effect of raising the status of
scientific research in the American value
system. The soft-spoken professor, with
umbrella and academic detachment,
achieved sudden and unprecedented
status. Consequently, academic re-
search on motion picture influences and
on factors which increase effectiveness of
motion pictures in training and informa-
tion has today achieved a prestige and a
measure of governmental support com-
pletely unknown before World War II.

The net effect of instructional film
research has been the renewed emphasis
in nontheatrical film production on
application of these techniques. Where

teachers failed to influence producers of
teaching films the research technician,
working under controlled laboratory
conditions and employing such terms as
"audience participation" to describe
what was formerly referred to as "re-
citing" and "classroom drill," has suc-
ceeded in raising by halo effect the
status of instructional techniques as a
recognized element of training and in-
formational films.

Our discussion of the relationship of
these two factors, i.e., (1) instructional
film research findings and (2) television
emphasis on rapid, low-cost program-
ming, to current trends and innovations
in training and informational film pro-
duction will be organized around three
topics: first, story treatment; second,
studio methods; and third, preproduction
analysis and planning.

I. Story Treatment

There are several things about the
story treatment of the Signal Corps'
experimental film, TF 11-1752 How to
Operate the Army 76mm Sound Projector Set.,
that were intended to serve the dual pur-
pose of cutting production time and cost
and increasing training effectiveness of
the film. First, we incorporated into
this film a number of instructional princi-
ples which have firm foundation in cur-
rent theory of educational and social
psychology. One such principle, long
stressed by William A. Brownell, dis-
tinguished educational psychologist, is
that instructional materials, to be in-
structionally effective, must be produced
so as to reflect process of learning, not sim-
ply the product of learning.

Following this dictum, story treatment
of TF 11-1752 was developed so as to
teach operation of the projector in the
way trainees actually behave in learning
this operation, and not exclusively to
demonstrate the way projectionists be-
have after they have learned and prac-
ticed their lessons.

To do this, two characters were cre-
ated: Jim, the trainee; and the off-

stage voice of the expert. This provided
two models for the audience: the one
who could be imitated immediately, and
the other who represented a model of
future performance. The technique of
the off-stage voice had been used previ-
ously by the Signal Corps in production
at the end of World War II of a series of
films on map reading.

Jim, the trainee, was carefully de-
veloped in the scenario and carefully
cast. His ability to handle the projector
set, clean it and operate it is established
on a level slightly above that of the com-
plete novice, but somewhat below that of
the expert. Occasionally, in the pic-
ture, Jim steps out of his role and for a
moment is master both of the machine
and of the practical aspects of the theory.
But, characteristically, Jim is the pleas-
antly alert and occasionally forgetful
American young man, temporarily in
Army uniform, who prides himself on his
ability to master machines and compli-
cated equipment.

Jim is objectified on the screen. He
can be seen and heard and his perform-
ance can be carefully observed and easily

Hoban and Moses: Cameo Production Technique

197

evaluated by the trainee audience. The
off-stage voice, on the other hand, is
transparent. The audience is free to
project physical characteristics, rank,
occupation and status into the off-stage
voice. His competence as an expert,
however, is thoroughly established in the
film — that, and no more. Preliminary
analysis of audience reaction to this film,
under actual classroom conditions, indi-
cates that the off-stage voice is dominant
in the film, and that the audience pro-
jects more desirable qualities into this
unseen character than to Jim, who ap-
pears in almost every scene.

In developing the story treatment into
which the characters of the trainee and
the experts are interwoven, two addi-
tional principles of instruction were
introduced. To be effective as a teach-
ing device, it was essential that the film
have a psychological organization rather
than a purely logical organization. Ex-
perience in projectionist training indi-
cates an impatience on the part of the
trainee with postponement of practice in
the actual threading and operating of
the projector, and lack of readiness for
instruction in assembly, inspection, pre-
ventive maintenance, nomenclature and
disassembly, until the point of operation
has been passed. Logical organization
of the treatment of the subject, based
upon identification and explanation of
component parts and on time sequence
of operations, would, it was assumed, go
contrary to the readiness of the audience
for instruction. The law of readiness is
an old concept in educational psychol-
ogy, and a valid one. Deliberately to
proceed in film instruction contrary to
this law would, at least theoretically, re-
duce the teaching effectiveness of the
film. The problem of logical versus
psychological organization of subject
presentation was solved, in part, by
backing into the subject. This was done
by opening the film with Jim, the
trainee, preparing to place the full reel of
film on the feed arm, and to thread and
operate the projector.

Another instructional principle intro-
duced into the story treatment was that
of interrupted action. An audience has a
tendency, amounting to a compulsion,
to complete an action once the action has
been started. Interruption and suspen-
sion of action before completion, or
omission of a part of a film obviously
included in the original version, tends to
create a tension in the audience which
can be satisfactorily discharged by com-
pletion of the initiated action or exhibi-
tion of the omitted part. This tendency
is well documented, and is closely related
to the well-known psychological phe-
nomenon of closure. The problem in
film production is to apply the principle
of interrupted action to story treatment
so that it operates to increase the in-
volvement of the audience in the subject
of the film and thereby increase learning
and retention.

The off-stage voice was used to accom-
plish this intent. Actually, the off-stage
voice served several purposes. As
already indicated, it constituted a trans-
parent model of expert knowledge and
competence in operation of the projector
set. Second, the off-stage voice, by
remaining off-stage, permitted individual
visual concentration on Jim, the trainee,
and on the projector set. Third, the
off-stage voice was used as a device, a
gimmick, if you will, for repetition and
emphasis of the important teaching
points of the film. Finally, the off-stage
voice was used as a device for inter-
rupting Jim's progress in threading and
operating the projector in order to insure
and insist on prethreading and pre-
operating checks, cleaning and projector
adjustment. Preliminary analysis of
field evaluations of this film, to which
reference has already been made, indi-
cates that, while the interruptions may
have annoyed the audience, the teaching
effectiveness of the sequences accom-
panying the interruptions appears to
have been strengthened.

Two other characters were used —

198

September 1952 Journal of the SMPTE Vol. 59

one, another off-stage voice somewhere
in the gallery; the other, a clearly visual
WAG. The Voice-from-the-Gallery
had a twofold purpose. The less im-
portant of these was that of a gimmick
used to sustain interest in the film by the
introduction of contrast and disharmony.
Generally speaking, nontheatrical film
producers act on the premise that it is
impossible to maintain audience interest
for thirty-odd minutes in a film dealing
with the operation and care of a piece of
technical equipment such as the JAN
projector set. This premise sometimes
approximates an article of credo in the
trade. Use of the Voice-from-the-
Gallery was a nod to this credo and a
form of insurance against possible waning
interest in the audience. The more im-
portant reason for use of the Voice-from-
the-Gallery was to simulate audience
participation in the demonstration and

explanation of the projector set. The
Voice-from-the-Gallery raised the kinds
of questions which, it was anticipated,
would exist in the mind of the audience.
In this way, the Voice-from-the-Gallery
' acted as audience protagonist during the
film showing. It was conceived as
somewhat of a character and no attempt
was made to disguise this conception in
the film. Approximately 10% of the
projectionist trainees resent this charac-
ter, but it is generally admitted that he
raised questions pertinent to the subject
of the film.

The Voice-from-the-Gallery was also
used as a device for emphasizing two
facts which needed to be established for
the audience: (1) the existence, im-
portance and usefulness of mimeographed
directions on operation of the projector;
and (2) the concept of the film as a
specific training aid, rather than a corn-

Fig. 2. ". . .the off-stage voice was used as a device for interrupting Jim's prog-
ress and for repetition and emphasis of the important teaching points of the film.

Hoban and Moses: Cameo Production Technique

199

plete course of instruction on operation
of the JAN projector set.

In shooting the picture, the Voice-
from-the-Gallery was recorded during
the noon-hour lull of one day of produc-
tion. The off-stage voice, however, was.
recorded in dialogue on the set simul-
taneous with the live action. This pro-
cedure was intended to increase the spon-
taneity and realism of the running dia-
logue between Jim and his off-stage men-
tor.

The fourth character in the film was
the WAG. The purpose of the WAG
sequence was to poke fun at the com-
plaints about the weight of the complete
projector set. The facts are that the
JAN projection equipment is heavy and
consists of three pieces. There is no
point in pretending in the film that these
facts do not exist. The alternative is to
attempt to reduce possible adverse reac-
tion to these factors. Contrary to some
expressed audience reaction, the WAG is
not a lady wrestler. Her facility in
carrying the projector and amplifier was
actually a facility in carrying an empty
projector and amplifier case supplied by
the prop department.

The WAG sequence is pure corn.
There is no objection to corn in an in-
structional film if it is useful as a means of
accomplishing one of the purposes for
which the film is made. The valid
objection to the use of corn in a training
or informational film is the use of corn
for its own sake. In general, the audi-
ence of projectionist trainees sees the
WAG as a device for combating gripes or
simply as a device to leave the audience
in a good mood.

Several other instructional techniques,
the importance of which has been indi-
cated in film research, were incorporated
into the film. The use of repetition has
previously been indicated. The thread-
ing of the projector was shown three
times. The use of the lens lever was re-
peatedly demonstrated. Care in re-
moval of the aperture and pressure
plates was repeated. Slow rate of de-

velopment was a must in acting, shooting
and editing. The instruction in the
film moves at a rate geared to a learning
audience. Except in a few instances,
subjective camera angle was employed, and
extreme close-ups were extensively used.
Repetition, slow rate of development and
subjective camera angle have been
shown in experimental film research to
measurably improve instructional effec-
tiveness of films demonstrating manual
operations.

Basic to story treatment and scenario
of this film was the concept of conflict and
the importance of conflict in the learning
process. If there are no obstacles to be
overcome, or no need to overcome
obstacles, there is little or no need to
learn. Hence the introduction of the
concept of conflict into the story treat-
ment. Throughout the film, there is the
continuing problem of whether Jim will
triumph over the machine or the ma-
chine over Jim. In counterpoint, is the
implicit and friendly conflict between
Jim and the off-stage voice. These
sorts of conflict prevail and are accepted
as challenges in the American culture.

The general principle of story treat-
ment of instructional films underlying
the Signal Corps' use of the conflict con-
cept in the experimental film is the de-
sirability, if not actual necessity, of taking
into account those characteristics of the
culture of a society which are dominant in
social behavior, and to incorporate these
cultural characteristics into films in
order to increase the audience acceptance
of the informational and instructional
content of the film. Perhaps more than
we realize, these cultural characteristics
may be extremely important to the
dynamics of film influence and film real-
ism than elaborate backgrounds, estab-
lishing sequences and the polished per-
fection of studio props.

Throughout the story treatment and
scenario preparation of TF 11-1752 was
the psychologically respectable but fre-
quently ignored idea that, since instruc-
tion has to do with learning, and learning

200

September 1952 Journal of the SMPTE Vol. 59

is done by the learner, the subject must be
approached from the point of view of the
learner. Training, informational and
propaganda films are often produced
from exactly the opposite point of view.

They consist of the expert presentation
of a subject by an expert on the subject
on the assumption that film is some sort
of magic medium of transmission of wis-
dom from the wise to the ignorant.

II. Studio Techniques

The term Cameo Technique is used
here to describe some of the studio tech-
niques applied to the experimental film,
TF 11-1752, in order (1) to cut time and
cost of production and (2) to increase
teaching effectiveness of the film. As
we all know, a cameo is a stone on which
a character is carved in relief. The TV
Cameo Theater is so named, presum-
ably, because of the exclusive employ-
ment of the cameo technique in video
presentation.

This technique consists of the omission
of background in the studio set, the in-

clusion of only essential foreground ob-
jects and characters, and the spot lighting
of these objects and character action.
Picturewise, these are suspended in an
enveloping blackness. Nothing is visible
to distract attention from the essential
characters and objects around which the
story treatment is built. Use of this
technique served the twin purpose of
simplifying studio production and of in-
creasing audience concentration on the
essentials of the subject.

In the production of the Army's film
How to Operate the Army's 76mm Sound
Projector Set, only one set was used, the

Fig. 3. "In the production of the film on How to Operate the Army's 16mm
Sound Projector only one set was used."

Hoban and Moses: Cameo Production Technique

201

walls of which were draped with gray
curtains, hanging in folds and following
the L-shaped pattern of the set. With
this L-shaped set, draped in such a man-
ner, only the screen, the speaker, the
projector and amplifier, the table for the
spare parts, and the actor required
lighting, and these by spots. The lack
of background permitted easy movement
of prop equipments for front, back and
side views; long shots, close-ups, reversal
shots, and relative constancy of camera
position and spot-light location and
regulation. The draped L-set (1) facili-
tated the rapid shooting of the picture
and (2) reduced the cost of set construc-
tion and lowered personnel requirements
for electricians and grips.

The general principle illustrated by
the Cameo Technique as used in the
Army's TF 11-1752, is that foreground,
not background, is the focus of action and
attention in a motion picture. The context
essential to perception of meaning is
shifted from more or less accidental and
purely situational settings, which vary in
any given operation, to a simple presen-
tation of crucial cues, consisting of mean-
ingful and irreducible wholes in which
elements, parts and fragments are em-
bedded.

Motion pictures have traditionally
been based de facto on a theory of fidelity
of representation. It has been assumed
that an audience can perceive the full
meaning of a picture only when a full
clutter of all visual background is faith-
fully photographed and reproduced on
the screen. Among other things, intel-

lectual activity consists of abstracting
essential meanings from the clutter of
context and situation. Where the pur-
pose of a film is to facilitate this intellec-
tual process of abstracting and analyzing
essential meanings and essential opera-
tions out of their contextual clutter, it
seems reasonable that the principle under-
lying the Cameo Technique actually
facilitates the desired audience response.
The usual studio treatment, based on an
exaggerated fidelity-of-representation
theory, may interfere with or at least not
substantially contribute to this end.

Another aspect of studio and story
treatment of TF 1 1-1752 which relates to
the ideas back of the Cameo Technique
is elimination of the conventional build-
up in the film of the introduction to the
subject. For the most part, elaborate
establishment of situations in order to
obtain audience rapport is unnecessary,
costly and time consuming for an audi-
ence reasonably sophisticated in the
subject.

In TF 11-1752, the film opened with
the projector set assembled and the pro-
jectionist preparing to thread the film
through the projector. The film is
intended for use in projectionist training
programs for military trainees, all of
whom have completed basic training and
presumably are aware that military
training is essential to successful military
operations and to personal survival, and
that training films are good training aids;
also, that the effectiveness of any film
presentation is greatly enhanced by good
projection of the film.

III. Preproduction Analysis and Planning

It is apparent that story, scenario and
studio treatment of the Army's training
film, TF 11-1752, involved both a great
deal of preproduction analysis and plan-
ning, and a working familiarity with
theory and research on the dynamics of
motion picture influence. If time and
cost of production were to be cut, in-
creased emphasis on preproduction anal-

ysis and planning was required. If the
effectiveness as a training and informa-
tional film was to be increased, then the
principles of effective instruction had to
be incorporated.

Preproduction analysis was needed in
three areas: (1) the audience, (2) the
objectives of the film, and (3) the situa-
tion of film use. In every motion pic-

202

September 1952 Journal of the SMPTE Vol. 59

ture situation, there are always two, not
just one, important parts: the audience
and the film. We started with the
audience.

There were two things which we were
required to know about the audience be-
fore we could effectively plan the film to
instruct, inform or otherwise influence
the audience: First, who was the in-
tended audience and what was it like?
Second, what did the prospective audi-
ence already know about the subject?

The anticipated audiences of TF 11-
1752 consisted of military trainees —
a cross section of American youth. They
are motivated by the typical American
drive to "get the job over with." Army
service is accepted as something neces-
sary to get the job over with, and Army
training is part of the job. Eight out of
ten of the draftees in today's Army have
received some high school education.
Fifty-five percent have graduated from
high school. Twenty-two percent have
attended college. For the most part,
these trainees have learned to learn.

Since these military trainees grew up
in industrial America and have had
considerable formal education in the
American school system, we assumed
that they were already familiar with the
following:

1. Electrical cords, plugs and outlets,
such as used in homes, schools, etc., as
conductors of electricity.

2. Flow of electricity through circuits,
controlled by switches.

3. Sound volume controls such as
found in radios, phonographs, televisions,
and other audio equipment.

4. Electrical motors, such as found in
vacuum cleaners, washing machines,
electric fans and mixers, and their func-
tional responsibility in the supply of
mechanical power.

5. Incandescent lamps, common items
in homes, schools, businesses, etc., as a
source of light.

6. Sound amplifying systems, such as
used in all radios, televisions, phono-
graphs, etc.

The objective of the film was to in-
struct the intended audiences, described
in the preceding paragraphs, so that they
would both feel competent to and be
able to perform the following operations
on the projector:

1. Preoperation check of electrical
connections.

2. Threading of film through the
projector.

3. Preoperation check on sound sys-
tem.

4. Prethread cleaning of film path.

5. Prethread and preprojection focus-
ing.

6. Replacement of projection and ex-
citer lamps, and other operating spares.

In addition, it was important that, in-
sofar as possible, the film influence the
attitude of the trainees toward the pro-
jector and its care and use. These atti-
tudes were spelled out, as follows:

1. The good projectionist uses com-
mon sense.

2. While the projector set appears to
be complicated, the mastery of the
equipment is not difficult if recom-
mended procedures are observed.

3. Careful checking and cleaning of
the equipment should be performed be-
fore each use.

4. The equipment is not too heavy for
men to carry.

5. There is more to learn about the
equipment than is shown in the film.

The film was produced for use in
organized Army projectionist courses.
In all such courses, ample provision is
made for classroom practice on the
projector set, under the supervision and
guidance of the instructor.

In the instructional procedure, the
training film, TF 11-1752, will be shown
immediately before the students are per-
mitted to handle the projection equip-
ment. A second showing of the film
will be scheduled at the end of the course,
just prior to the period for the qualifying
examinations. Another Army training
film, TF 11-1574 Technique of Good Pro-

Hoban and Moses: Cameo Production Technique

203

jection, is already being used in the course
and will continue in the schedule, to
show the importance of good projection
in the classroom and how this is accom-
plished.

With such advanced knowledge of the
situation of use, the instruction and prac-
tice to follow the showing of the film, and
the availability of a sister film covering
projection techniques, it was possible to
limit the content of the film to the essen-
tials of prepractice instruction. Fur-
thermore, the fact that the audience was
enrolled in a projectionist training course
made it possible to eliminate the "estab-
lishing sequences" and to open directly
on the subject. Assembly and disassem-
bly of the equipments were omitted
from the film, since these operations are
taught in the practice phase, working
directly with the equipment.

Considerable experience gained from
associating with projectionists and teach-
ing projectionist training courses, and
considerable thinking on the objectives
of the film in terms of audience perform-
ance and audience attitudes toward the
Army projector set, went into the first
treatment of the story outline, prior to
conferences with the writer regarding
scenario preparation. The nature of the
audience, the assumptions on existing
knowledge of the audience, the objectives
of the film in terms of performance and
attitudes, and the situation of film use
were spelled out in advance of the
scenario-planning phase.

We encountered no difficulty, no mis-
understandings, no obstruction and no
opposition anywhere along the line, once
performance specifications were clearly
set forth for all to examine.

204

September 1952 Journal of the SMPTE Vol. 59

Auditorium Specifically Designed
for Technical Meetings

By D. MAX BEARD and A. M. ERICKSON

The Naval Ordnance Laboratory, White Oak, Mel., is not only a research
and development center for ordnance material, but it has also become a
center for the dissemination of scientific information. Technical meetings
and symposia of international fame have been held in the auditorium, specifi-
cally designed for such meetings, seating 550, with optimum acoustics.
Included are a console for control of 21 microphones, telephone communica-
tion with the moderator, and controlled levels to sound recording facilities.
The projectionist has direct contact with the speaker, the console, the thyra-
tron-controlled overhead lights, and preset stage lighting. Complete audio-
visual aids are available.

JL HE NAVAL ORDNANCE LABORATORY
has the primary objective of the de-
velopment of new and better ordnance
for the United States Navy's Bureau of
Ordnance, and is destined to become one
of the outstanding research centers of
the nation. It must be realized not
only that it is essential to equip this
research activity with the most modern
and complete facilities, but also the
laboratory must be equally well equipped
with a staff of fully informed scientific
personnel.

It was recognized late in World War
II, while planning for the new laboratory
at White Oak, Md., that every effort
should be expended to maintain ade-
quately trained technical personnel to

Presented on April 22, 1952, at the Society's
Convention at Chicago, 111., by D. Max
Beard, Naval Ordnance Laboratory, Silver
Spring, Md.

make and keep this laboratory a note-
worthy research center — whether at
war or in peacetime. As a result of
these efforts, this laboratory has, in
addition, become an intellectual center
for the dissemination of scientific in-
formation. It is for this phase of
endeavor that its auditorium was planned
and is dedicated.

The lot of the scientist speaker is not
always an easy one. His subject is
usually one that must be closely followed
and have a minimum of interruptions.
He must have full assurance that he can
be heard or that his visual aids are
clearly discernible to the entire audience.
Of equal importance is the comfort of
his audience, who must expend a con-
siderable amount of mental effort to
keep up with the subject, and certainly
cannot do so if there is an accumulation
of distractions such as hard seats, foul

September 1952 Journal of the SMPTE Vol. 59

205

Fig. 1. The NOL auditorium showing lectern in its normal position,
with microphones in place for audience participation. Questions may
also be written down and handed to assistants at the aisle mikes.

Fig. 2. Visual aids, such as opaque projection, Viewgraph, charts, blackboard,
pointers, etc., are readily available to the speaker even when presenting his talk
to a small group from out in front of the stage. Microphones are strategically
placed to give the lecturer as much freedom as possible, while at other times
lapel microphones are used. Floor outlets would be preferred to the present
outlets along the front of the stage.

206

September 1952 Journal of the SMPTE Vol. 59

Fig. 3. Rear of the auditorium showing the location of the control console,
the contour of the rear wall and the projection-room parts.

air, disturbing lights and poor audi-
torium acoustics. The NOL audi-
torium is designed to put both the
speaker and his audience at ease.

The major points considered in the
design of this auditorium were: (1)
audience comfort; (2) intelligibility;
(3) availability of visual aids; (4) con-
trolled levels of illumination and sound;
and (5) flexibility of the overall system.
The facilities for these results are herein
described.

Several members of this Society gave
excellent advice, and were instrumental
in the final design and engineering of the
auditorium. Since most contacts were
made through the Society, the writers
would like to express their appreciation
to the Society for this assistance. How-
ever, special mention is made of the
work of Al Ward and John Volkmann
of the Radio Corporation of America
who were responsible for the acoustics
and sound system engineering, and J.
E. Currie of the National Theatre
Supply Company who assisted in the
layout of the projection sound system on

the stage and in the projection booth.
The Photographic Division of this
laboratory is responsible for the further
tailoring of the installation in its present
exacting requirements and its operation.
The auditorium, seating 550, has a
reverberation time of approximately
0.75 sec, which is slightly less than that
of a comparable-size (200,000-cu ft)
motion picture theater (see Figs. 1, 2
and 3). To achieve these desirable
acoustics, and to keep within the struc-
tural limitations of the building, the
interior was altered to include poly-
cylindrical sections, sloping floors and
a serrated rear wall. Absorbing ma-
terial was selected and placed to give
optimum acoustics, with side walls
surfaced with acoustic plaster, the
ceiling of standard plaster, and over-
stuffed theater seats. An on-the-stage
lecturer with good speaking quality
may be easily heard at the rear of the
auditorium without the aid of sound
reinforcing. These acoustic properties
are not only desirable for lectures, but
are ideal for recording purposes.

Beard and Erickson: Auditorium for Technical Meetings

207

The stage is similar to small theater
installations with several added features
such as: (1) a one-ton hoist for moving
equipment for demonstrations; (2) alter-
nating- and direct-current power, signal-
ing and microphone outlets available
at various points; (3) microphones
behind the projection screen, permitting
the speaker to have complete freedom
from the lectern; (4) removable pro-
jection screen and motion picture
speaker systems; and (5) sound rein-
forcing speakers overhead and slightly
in front of the stage in the proscenium
arch.

The projection booth, shown in Fig. 4,
is equipped to handle 16mm and 35mm
motion pictures, and 2 in. X 2 in.
standard and continental lantern slides.

The standard-size dissolving slide
projector was altered to accommodate
1000-w incandescent projection lamps,
with special blowers and heat-resistant
glass to permit prolonged projection of

negative lantern slides. This is quite
important since some scientists may
discuss one lantern slide for as long as
ten minutes. House-light dimmer and
curtain controls are located in the booth
at each of the viewing ports. The stage
light control is centrally located.

Slide-changer buzzer, auditorium
monitor, intercommunication and tele-
phone communication are readily ac-
cessible to most of the normal operating
positions. Accurate focusing of all pro-
jectors is accomplished by means of a
seven-power monocular sight that is
movable to each viewing port. In
addition to the monitor speakers on the
two sound channels, a sound-level
meter is bridged across the stage speaker
bus and provides a positive indication
of sound level being delivered to the
auditorium.

The auditorium sound reinforcing
system (Fig. 5) is designed to be con-
trolled from a mixing console (Fig. 6)

Fig. 4. The projectionist utilizes a monocular sight to get accurate focus
on all projection from the booth. The dissolving slide projector controls
and modified heat-dissipating system may be noted on the projector at
the right of the operator.

208

September 1952 Journal of the SMPTE Vol. 59

2 PROJECTION SPEAKER LINES
STAGE BOOTH TELEPHONE

AUDITORIUM LIGHT REMOTE CONTROL
FRONT CURTAIN REMOTE CONTROL
SCREEN CURTAIN REMOTE CONTROL
BOOTH MONITOR
SLIDE BUZZER

6 LINES TO REC RM

2 SPARE LINES

OUTSIDE TELEPHONE

12 LINES TO P A RM

2 LINES TO CAFETERIA

2 LINES TO LOUNGE

PHONE TO CENTRAL REC

INT COM TO CENTRAL REC

9 AISLE MICROPHONE LINES

Fig. 5. Schematic of sound and control services. The entire operation for
limited services may be controlled from the projection booth, utilizing preset
levels at the control console.

Fig. 6. The operator of the control console not only has a clear view
of any activity in the auditorium, but has complete control of all sound
facilities by means of switches, attenuators for sound reinforcing and
recording.

Beard and Erickson: Auditorium for Technical Meetings

209

at the rear of the audiiorium. This
console contains 21 microphone pre-
amplifiers and 2 line amplifiers. As
many as 12 circuits can be mixed at
one time with provisions of level adjust-
ments on each circuit. One of the two
output circuits drives the sound re-
inforcing amplifiers and the other may
be patched to the sound recording
facilities, or to other areas on the base
at NOL. Communication facilities are
available with the symposium modera-
tor, projection booth, backstage and the
recording room. The outside telephone
is provided with a light signal rather
than a bell so that incoming calls do
not disturb the lecturers.

This control console mixer system is
particularly adapted to audience par-
ticipation. The operator with his com-
mand view of all microphones on stage
and in the aisles can switch in micro-
phones or interchange and maintain
levels as required. The result is excel-
lent sound reinforcing of all pertinent
discussions regardless of whether they
are between the lecturer and a par-
ticipant from the audience, or among
two or three members of the audience.
This flexibility is extremely valuable
where it is desirable to record every word
of international symposia.

The auditorium is utilized in many
different ways:

(1) For week-long symposia, nearly
every facility must be made available
to include audience participation, all
projection services, lapel microphones,
lectern, projectionist working from
scripts, intercommunication with outside
activities, and complete sound record-
ing, which includes all verbal combats
between members of the audience.
Performances of this type have not only
been completely recorded, but tran-
scribed and eventually published in
book form.

(2) Seminars.

(3) Public-speaking training courses.

(4) Junior professional training.

(5) Intra-Defense Department dis-

cussions. Many interesting situations
come up that can hardly be avoided.
Difficulties will probably always arise
wherein some lecturers fail to have
their slides in order or properly marked,
and where they are frequently of such
a nature that only the speaker himself
can tell which is the top of the slide, or
other speakers who in their nervousness
continually press the buzzer to the pro-
jectionist indicating a change of slides.
The projectionist, in his effort to make
one change per buzz, may run several
slides ahead. Another problem occurs
when two audience participants of de-
cidedly unequal voice levels are at
microphones on the same console control
switch. Conflicts of this type have
been eliminated by repatching; how-
ever, some problems can hardly be
corrected by modification of the facilities.

There are several improvements that
are highly desirable in an auditorium
designed for this type of operation.
Most noticeable among these are the re-
quirements for panels for the use of
charts, etc., that may be pushed off
stage when no longer required; more
complete facilities in front of the stage
for small groups; a system of lights on
lectern (in view of the speaker only)
controlled by the moderator, to warn
the speaker he is lecturing beyond his
allotted time; an improved system of
microphones for audience participation;
screen set flush with the rear of the stage;
acoustic baffles on the air-conditioning
ducts; a stereophonic sound and pro-
jection system; acoustic treatment in
the booth; and possible use of variable-
focal-length lenses for 2 in. X 2 in. slide
projection. The magnetic sound track
on 16mm film will be a boon to the
functions of this auditorium.

The auditorium at NOL, although
originally planned about seven years
ago, has been kept up to date in most
respects and has proven most satis-
factory in nearly every respect for the
type of performance required of it. Of
the five major points considered in the

210

September 1952 Journal of the SMPTE Vol. 59

original planning: audience comfort,
intelligibility, availability of visual aids,
controlled levels of illumination and
sound, and flexibility, the one most
overtaxed has been the last. There
have never been any regrets that every
consideration was given to this in the
early planning, and the extra lines,
conduits, etc., that were included in the
original design have made it unnecessary
to make any major or expensive altera-
tions to the auditorium.

Discussion

George Lewin (Signal Corps Photographic
Center}: I wonder if ybu've ever given any
thought to providing a remote-control of
focus on either your slide projectors or
your motion picture projectors, so they
could be controlled, say, either from the
lectern or by somebody in the audience.

Max Beard: We have never tried that.
Does it work pretty well?

Mr. Lewin: Well we use it to some
extent in running dailies, because there's
always a question as to whether the pro-
jectionist has the same idea about focus
as the audience.

Mr. Beard: I wonder if the speaker
close to a screen could determine the focus
as accurately as the man from the booth
with the telescope;

Mr. Lewin: Well, probably not the per-
son near the screen, but somebody in the
audience, that is somebody assigned, of
course, by the speaker could take care of
that.

Mr. Beard: It's of interest to point out
that very often when you're running film,
the film goes in and out of focus at times
for reasons beyond the control of the pro-
jectionist (he's not always watching it that
closely).

Chauncey L. Greene (RKO Orpheum Theater,
Minneapolis}: I've used the seven-power
binocular for checking focus as well as

trying to control it from near the screen.
My personal experience has been that the
Navy seven-power binocular critically
focused beforehand upon a target located
near the screen is far superior to trying to
control it from a position near the screen,
because you have really a more critical
view of what you are trying to do. I've
never had much success with a monocular,
and a poor quality binocular is worse
than useless, but that 7 X 50 Navy glass
is probably the world's finest for this
purpose. True, if you try to operate the
entire projection establishment single-
handed, it is not going to receive the
attention that it deserves either through
binoculars or without them. Lastly, might
I express an opinion that this Society
could render no greater service than to
mail a reprint of this paper to the Visual
Education Department of every college
or institution of learning in this country.

Mr. Beard: Thank you, Mr. Green.
There's an additional comment I might
make. The biggest problem we have,
when focusing, is the shifting from 3^ in. X
3J in. to a 3J in. X 4 in. lantern slides.
The projector we have has different
positions for these two types of slides,
which means that every time you project
the continental slide (3| in. X 3J in.)
you have to refocus the projector. This
is a big problem with us, since we fre-
quently get a mixture of the continental
and standard slides.

Chester Beachell (National Film Board of
Canada}: Have you any facilities in this
auditorium for providing different screens,
such as perforated matte, a beaded screen,
or a silver screen for a Polaroid stereo
projection?

Mr. Beard: We use the perforated screen
for all projection. We have not tried the
Polaroid system; however, we are quite
anxious to do so some day.

Mr. Beachell: It has been my experience
that a matte screen won't work on Polaroid
stereo at all. It scrambles the light
polarity.

Beard and Erickson: Auditorium for Technical Meetings

211

Safety Requirements in Projection
Rooms and Television Studios

By SAMUEL R. TODD

Nitrate film has imposed special requirements on projection-room design for
many years. The advent of 35mm safety film may change some of these,
and this possibility is discussed. The increasing use of films, both nitrate
and safety types, in television studio operations calls for similar precautions,
and the presence of considerable electronic equipment adds to the normal
hazards. These hazards and certain others peculiar to live program pres-
entations are discussed. Safety problems involved in the installation and
operation of high-voltage television equipment in theaters are outlined.

PROJECTION ROOMS IN MOTION PICTURE THEATERS

Since the first "Nickelodeon" opened
its doors to the public for presentation
of motion pictures the greatest safety
hazard, as is well known, has been the
fire and panic danger inherent in the
ever-present possibility of accidental
ignition of the thousands of feet of
cellulose nitrate film located in the
projection room. This continuing haz-
ardous condition over the years has been
changed recently, to a considerable
degree, due to the gradual replacement
of nitrate film by the so-called "safety"
cellulose acetate film. However, as
long as 35mm film remains standard
for the projection of motion pictures in
theaters, most safety authorities, many
theater owners, and those theater de-
signers who are intimately conversant

Presented on May 3, 1951, at the Society's
Convention in New York, N.Y., by
Samuel R. Todd, 4711 Woodlawn Ave.,
Chicago, 111.

with the numerous details involved in
the proper design and construction of
modern projection rooms for maximum
safety and best operating features, feel
that any changes in the specifications
now considered as standard are both
unwarranted and undesirable. If we
assume, and it is a fair supposition, that
a fireproof type of construction for
theaters will continue to be demanded
by local governmental authorities, it
seems hardly possible that nonfireproof
type of construction for projection rooms
would be advocated.

Let us consider, item by item, some
of the real reasons for the present type
of enclosure for the projection, sound
and accessory equipment in the modern
theater projection room. To isolate
from the auditorium unavoidable noises,
such as those due to the operation of
equipment and due to conversation
necessary from time to time, a sub-

212

September 1952 Journal of the SMPTE Vol. 59

stantial enclosure is certainly needed.
The physical strength alone required
to safely support the weight of the
necessary equipment, and to allow for
the additional weight of four or more
persons who may be in the room at one
time, calls for the specification of a
heavy reinforced concrete floor con-
structed according to the recommenda-
tions of a qualified structural engineer.
Also, and for similar reasons, the four
walls of the room should be designed to
assure structural security and adequate
fire protection as well as the necessary
physical strength required to support
electrical raceways and heavy equipment
items which may be mounted on these
walls. From long experience in pro-
jection-room design, it seems advisable
to call for ceilings not less than 9 ft
above the projection-room floor level,
and of structurally strong and fireproof
construction. Costly films, sound and
projection systems need protection from
theft and from fire hazards elsewhere in
the theater as well as vice versa. Solid,
fireproof enclosures, with approved fire-
proof doors equipped with trustworthy
locks, are thus well justified whether or
not the films used introduce any special
fire hazards.

In the event a fire does occur in the
projection room, it is instantly and im-
peratively necessary to completely isolate
the room from the auditorium in order
to prevent possible audience panic.
Panics kill far more people than actual
fires do. Projection and observation
port openings must be equipped with
gravity-operated, automatically con-
trolled, approved steel fire shutters
actuated by a master control cord and
by 160° fusible links, located imme-
diately above and within 6 in. of the
upper magazine of each projection ma-
chine. In the event of a projection-
room fire, it is necessary to exhaust
promptly all smoke and odors to the
outside air. This may be accomplished
by means of an adequate, forced-draft
ventilating system; this system may also

serve to exhaust normally the gases and
carbon ash from carbon-arc lamp
enclosures. A natural gravity vent, with
adequate cross-sectional area extending
through the projection room ceiling
directly to the outside air, should also
be provided as protection in case of
failure of the electricity supply service.

Consideration should be given to the
dimensions of the projection room in
order to provide normal operating safety
factors for the projectionist. The room
should be not less than 12 ft between
front and rear walls, in order to have
sufficient working and free walking space
around all equipment. The rewind
table should be located at the rear wall
equidistant from the two projectors.
The space between projectors should
be sixty in. at the lens centers and there
should be a clear space from the lens
centers of 48 in. both to the right of the
righthand projector and to the left of
the lefthand projector. A modern de-
sign for the rewind table includes space
beneath the table top for locating
approved-type film containers, sup-
ported several inches above the floor.
In order to deliver on the screen the
high-quality performance expected from
the projectionist, he must at all times,
while on duty, be reasonably calm and
alert both mentally and physically.
These considerations, as well as those
of common decency, call for providing
adequate modern toilet facilities and a
lavatory with both hot and cold running
water in well-designed theater projection
rooms.

This brief review and discussion of
present safety requirements in theater
projection-room construction is intended
to justify the conclusion that practically
all of the requirements are in order
regardless of the type of film used.
They obviously must not be relaxed
in any degree so long as there is a
possibility that even small quantities
of cellulose nitrate film may reach the
theater, and this possibility may be
with us for years to come. Entirely

Samuel R. Todd: Safety Requirements in Projection

213

apart from this, . however, it has been
shown that they lead to improved pro-
gram presentation and better general
safety conditions for both the public and
the theater personnel. This is import-
ant; twenty years of good engineering
design and proven operational practices
have created public confidence in theater
safety. This could be destroyed by a
single instance where loss of life was

rightfully or wrongfully attributed to a
relaxation in the presently accepted
standards. Furthermore, it should be
kept constantly in mind that there is
no moral defense for anyone who may be
responsible for deliberate laxity in the
construction and operation of theater
projection rooms if a fire does occur and
the sordid picture of a disastrous panic
is the tragic result.

TELEVISION INSTALLATIONS

Projection Rooms

The equipment necessary in television
station projection rooms creates possible
hazards of the same type inherent in
the projection rooms of motion picture
theaters. With the present use of 35mm
film and projectors equipped with the
Synchro-Lite, instead of the conven-
tional carbon-arc lamps, hazards affect-
ing the safety of the operating personnel
are definitely and continuously present.
For example, this gas-discharge gap
lamp employs potentials up to 5000 v
across its terminals. The standard mo-
tion picture projection equipment, as
observed in television station projection
rooms, consists of two 16mm projectors
and two 35mm projectors, each equipped
with the Synchro-Lite as the light source.
As long as 35mm film continues to be
used for programming purposes, the
hazard inherent in the possible use of
nitrate base film will require the ac-
ceptance of safety regulations as here-
tofore found necessary in the projection
rooms of motion picture theaters.

The panic that may be created by the
sudden and violent combustion due to
the ignition of perhaps a thousand or
more feet of nitrate film, or the un-
comfortable situation incident to one
of the operating personnel lying prone
from the effects of an electric shock, are
possible situations requiring very special
consideration from those individuals
charged with the responsibility for
formulating safety rules and regulations
for television station projection rooms.

The safety requirements for projection
rooms in television stations should
include as a minimum: (a) standard
fireproof construction of the projection
room; (b) the proper floor dimensions
to provide good operating conditions;
(c) approved storage facilities for the
film; (d) an approved rewinding device
for 35mm film; (e) the installation of
approved, self-closing, automatically con-
trolled fire shutters for the port holes;
(f) the proper projection-room ventila-
tion, including both gravity and forced-
draft methods; and (g) the provision
of adequate means for instant exit for
the operating personnel through open-
ings equipped with fireproof self-closing
doors opening outward. As in the case
of theater projection rooms, nearly all
of these requirements are fully justified
on a simple common-sense basis without
any consideration of the special hazards
introduced by the possible use of cellulose
nitrate film. A typical television pro-
jection room incorporating the design
features which have been mentioned
would be self-contained, having the
moving picture machines project the
light through a wall directly into the
camera chain located in the adjoining
room. Figure 1 shows in detail some
of the safety features incorporated in a
typical well-designed television studio
projection room.

Studios

With the increasing use of a great
variety of household appliances in the
production of television programs, haz-

214

September 1952 Journal of the SMPTE Vol. 59

' Fig. 1. A typical well-designed television studio projection room showing in some de-
tail some of the safety features.

ards are being introduced which require
continuing alertness on the part of the
producing and operating personnel.
For example, in the demonstration of
open-jet gas ranges the possibility of
conflagration in the studio is always
present. Perhaps to a lesser degree
this also applies to the use and demon-
stration of electric ranges and other
electrical appliances with exposed heat-
ing elements.

In the larger studios, with arrange-
ments for seating studio audiences of

50 to 100 persons, the producing and
operating personnel must ever be alert
to unforeseen accidents that may cause
a panic. Figure 2 shows a typical, large
studio with the possibility of having
large numbers of people confined within
its walk and hence subject to all the
usual and unusual panic hazards. In
addition to the possible hazards just
mentioned, special attention should be
given to the safe installation of heavy
lighting equipment, whether such equip-
ment is directly suspended from the

Samuel R. Todd: Safety Requirements in Projection

215

ceiling or mounted on balconies, and to
adequate supports for heavy lighting
units at the floor level. These pre-
cautions should also apply to special
rigging apparatus used to support and
shift special scenic effects, and to all
stage properties. In these larger studios,
where relatively large groups of people
are admitted, adequate exits with
approved illuminated directional signs
should be provided. Figure 3 shows the
extent of the special lighting equipment
and other production apparatus which
may be encountered in a typical modern
studio.

Theater Television Using
Direct Projection

The installation of theater television
equipment has introduced problems
not heretofore present in providing
motion picture screen presentations.
Essentially, the equipment purchased
by the theater owner for such an installa-
tion consists of three major items: (a)
a high-voltage supply unit weighing 800
Ib and providing 20,000-v and 80,000-v
output circuits; (b) video control ampli-
fier units mounted on conventional racks
and weighing 1200 Ib; and (c) a picture
projection unit which with its mounting
trunnion weighs 400 Ib. This by no
means small extra weight of over a ton
introduces a definite safety hazard to the
building structure in many instances.
Structural loading factors need to be
thoroughly checked before the installa-
tion of such massive equipment.

Because of the high potentials pro-
duced by the voltage supply unit it is
essential that it be located in a separate
fireproof room with the entrance door
closed and locked at all times. It is
preferable to locate the unit as near as
possible to the optical barrel which
encloses the picture projection tube in
order to reduce the required length of
the special 80,000-v cable which con-
nects to the second anode of the picture
tube.

The video amplifier unit is mounted
on two racks occupying a floor space
40 in. wide and 18 in. deep extending
to a height of 64 in. in the theater pro-
jection room. It contains a television
receiver, monitor panel, control panels,
low-voltage power supplies and other
miscellaneous operating units. While
required projection-room space is not
large, the room dimensions should
provide enough to avoid overcrowding
and consequent reduction in normal
operating safety factors.

The proper location of the picture
projection tube and optical barrel is
very important from the viewpoint of
safety to the public and it is also a very
important factor in securing best pro-
jection quality. The nominal "throw"
from the projection unit to the screen
is 60 to 65 ft. In a typical installation,
a heavy steel platform was installed for
mounting the optical unit. This plat-
form was mounted on the front face of
the first balcony rail in such a manner
as to preclude any possibility of un-
authorized persons having access to or
coming in contact with the projection
tube or any of its high-voltage terminals.
In this position, the tube and optical
barrel projected a 15 X 20 ft picture on
the screen at a "throw" of 62 ft. In
theaters having no balconies the pro-
jection unit must be supported from
the floor or ceiling and, as in the case
of balcony support, the mounting struc-
ture must be adequately designed to
eliminate any possibility of either elec-
trical or mechanical hazards to theater
personnel or audience. The unit should
be enclosed in such a manner that any
corona or arcing due to dampness is
not visible.

Presently available direct projection
television equipment is very well de-
signed from the viewpoint of having
adequate safety disconnect switches at
all points where dangerous potentials
may be encountered. Switches are
provided, for example, at the access door
to the high-voltage power supply room,

216

September 1952 Journal of the SMPTE Vol. 59

Fig. 2. A typical large studio showing the possiblity of accommodating large

numbers of people.

Fig. 3. A typical modern studio showing the extent of the special lighting equip-
ment and other production apparatus which may be encountered.

Samuel R. Todd: Safety Requirements in Projection

217

on the enclosure for the picture pro-
jection tube and on various components
of the amplifier and control equipment.
It is extremely important that all of these

safety circuits be intact at all times.
Unauthorized modifications are the
height of foolishness where potentials
dangerous to life are concerned.

FILM METHOD FOR THEATER TELEVISION PROJECTION

This method, the so-called storage-
type system, for television theater pro-
jection uses a 35mm motion picture
camera to photograph a negative image
on a television receiver to produce a
direct-positive print. The exposed film
is transported continuously to equipment
for rapid development and drying.
From this equipment it is transported
to the projector for immediate projec-
tion on the theater screen. The elapsed
time from the television camera pickup
at the scene of action to the time of
projection of the completed positive
print on the theater screen is 61 sec.

This method requires a properly
ventilated room of fireproof construction
for the television receiver, the 35mm
picture camera with a magazine which
may contain 12,000 ft of unexposed
film, and for the developing and drying
equipment. This room obviously must
be adjacent to the theater projection
room and provision must be made for
feeding the completed positive print
to the upper fire valve rollers of the
theater projector, from which the upper
magazine has been removed. This
arrangement of equipment will provide
a continuous projection of motion pic-
tures on the theater screen for more
than two hours' duration.

From the viewpoint of safety, the
present method used for feeding the
processed print to and across the
theater projection room to the projector
head on a series of open pulleys could
hardly be considered as complying with
the most elementary standards for safe
handling of 35mm film.

With the take-up magazine and the

take-up device on the projector de-
signed for only approximately 2000 ft
of film, it is obvious that cutting of the
film at the end of each 2000 ft will be
required. The running end of the film
must quickly be attached to the hub of
an empty reel and the excess film on the
projection-room floor must be spun
onto the hub, after which the reel must
be placed into position on the take-up
spindle of the lower magazine for taking
up the succeeding 2000 ft of film. This
procedure must be repeated five times
during the continuous projection of
1 2,000 ft of film. Such a procedure does
not appear to follow any of the long-
standing practices for the safe handling
of motion picture film.

Conclusions

Some of the safety hazards in theater
and television studio projection rooms
have been pointed out and the import-
ance of adequate corrective measures
has been emphasized. The special safety
precautions developed over a long period
for theater projection rooms have been
shown to be sensible and desirable
without regard to the ignition charac-
teristics of the film used, and the same
considerations are shown to be ap-
plicable also to television studio pro-
jection rooms. Special hazards in tele-
vision studios have been outlined.
Theater television equipment, which
presents safety hazards of new types,
has been discussed and attention has
been called to some of these in the hope
that full knowledge of them will aid in
their eventual elimination.

218

September 1952 Journal of the SMPTE Vol. 59

Military-Type Lenses

for 35mm Motion Picture Cameras

By PAUL G. FOOTE and R. E. MIESSE

A new series of lenses for 35mm motion picture cameras has been designed as
the first to primarily meet the many detailed requirements of military use.
These are designated by the name Millar, and represent the achievement
of new goals. It has been a joint development by two companies who pooled
resources and experience to provide a series in a minimum of time and cost
with high performance. Many mechanical features have been combined
with top optical performance to provide dependable operation over a wide
range of conditions.

1. General Description

The Miltar series of lenses was
planned to incorporate features required
for military use, but not generally pro-
vided in lenses made for commercial or
studio use. In specifications for either
lenses or cameras appear requirements
for vibration, humidity and temperature
range tests more stringent than any
commercial needs, which were con-
sidered in all details of the design of these
lenses. Wherever possible, the recom-
mendations of MIL-STD-150 were fol-
lowed. In the specification list of lens
types, these are: "Type V, for 35mm
motion picture cameras."

The series is available in black for
general use, as shown in Fig. 1. There
is also a series in gray for the A-6
Camera, a portable 35mm motion

Presented on April 22, 1952, at the Society's
Convention at Chicago, 111., by Paul C.
Foote, Bell & Howell Co., 7100 McCormick
Rd., Chicago 45, 111., and R. E. Miesse,
General Scientific Corp., 5151 W. 65 St.,
Chicago, 111.

picture camera for the Government
services.

The equivalent focal lengths of the
lenses in the series are based on a
modified geometric progression of ap-
proximately V2, or 1.4X intervals,
which give an area change of 2 from
one lens to the next (Fig. 2). These are:

1-in., 25mm
1.4-in., 35mm
2-in., 50mm
3-in., 75mm

4-in., 100mm

6-in., 152mm

10-in., 254mm

The 3-in. and 6-in. depart slightly
from the exact values in the series
because of the previous use of these
focal lengths, and the 10-in. was included
for the same reason. The first pro-
duction included all but the 1.4-in.
and 3-in., but these are now available.

The focal length of all lenses has been
coded by the use of dots just ahead of
the word "feet" on the focusing jacket
in order that matched pairs, for stereo
or other uses, could be picked from
production lots without needing further

September 1952 Journal of the SMPTE Vol. 59

219

Fig. 1. Miltar Series in black for general use.

Fig. 2.

measurements. It keeps high focusing
scale accuracy without individual cali-
bration. Focal lengths are segregated
into three groups, which are

plus 2% to plus 1%, three dots,
plus 1% to minus 1%, one dot, and
minus 1% to minus 2%, two dots,

and assembled into the focusing jackets
that have been engraved, particularly
for each group, and coded in accordance
with the above ranges. The majority
of the lenses fall into the nominal group:
plus 1% to minus 1%, one dot.

These lenses are mounted in
military standard mount (Fig. 3) also
identified as the Bell & Howell Eyemo
mount, but they will also be availabl
unmounted, or mounted in studio-type
focusing jackets for the Bell & Howell

Graph of effective focal length Design 2709, the Mitchell, Wall or other

and magnification steps. cameras.

MILTAR LENSES
FOCAL LENGTH PROGRESSION /

HICAGC

WELL
EPT. C

2
1.4

LENGTH-

a HO

ENG.D

3
S

BELL
riCAL

TION

MAG

op-

MIFIC/

L4 2 2.8 4 5.6 8 1

220

September 1952 Journal of the SMPTE Vol. 59

2. Optical Characteristics

In mapping out this Miltar series,
some limitations were imposed on
diameters to permit mounting lenses on
existing camera turrets. The type of
lens was then chosen to provide maxi-
mum performance. The 1-in. through
4-in. are 6-element construction of the
Speed Panchro or Biotar form, with
apertures of //2, or T2.2.

The size restrictions limited the 6-in.
to//3.5, or T3.7, permitting the use of a
well corrected triplet. The 10-in. is
limited to //4.5, or T4.9, and is a 4-
element telephoto of standard form.
In each case a special effort was made to
use readily available domestic glass.

This glass, however, is held to closer
than normal commercial index and
dispersion tolerances.

The performance of all focal lengths
is substantially increased over lenses
previously supplied and is comparable
to the best studio lenses. The aberra-
tions have been corrected to give a crisp,
high contrast image over the full frame.

The curves showing the aberration
corrections are given in Figs. 4, 5, 6,
7, and 8. Part of the information is
from the design data, part from actual
measurements of production lenses.

No attempt is made here to quote
resolution values, as the performance
requirements of these lenses are based
on results in specific cameras. Tests on
spectroscopic plates do not give com-
plete information, and tend to give a
false appraisal of the practical values
because of contrast differences.

Vignetting has been reduced on all
focal lengths. This has required es-
pecially careful balancing of the oblique
aberrations to obtain the improved
contrast and resolution in the outer
portions of the frame.

All air-glass surfaces are coated.
Cemented elements will withstand the
full temperature range and thermal shock
requirements of the specifications.

3. Mechanical Characteristics

In the styling and general design, care
was taken to give the lenses a matched
series appearance. The diameters and
physical lengths are in steps to correspond
with the focal lengths and apertures.
Special attention has been given the
mounts and glass to obtain rugged con-,
struction for meeting thermal shock,
temperature range, humidity, vibration
and mechanical shock tests.

In designing this series to meet the
drastic vibration requirements, every
part is locked into its respective assembly
with special antivibration sealing com-
pounds and deep-set pilot screws, which
again are locked into place so securely
that they can only be removed by
drilling.

The lenses are completely operable
over the temperature range of — 65 F
to +160 F. All tolerances have been
computed to offset the size changes for
expansion and contraction through the
temperature ranges.

A special noncorrosive lubricant is
used which is not affected by these
changes. This lubricant has a vapor
pressure so low at 160° that no deposit
on the glass is detectable after sustained
operation at that temperature.

The diaphragm blades are lubricated
with an unusual type of material,
guaranteeing perfect operation over
the full temperature range, with a long
operating life. It has the properties
of being anti-icing and noncongealing,
at extremely low temperatures. Glob-
ules of condensed moisture will not
freeze to the leaves, and the lubricant
itself will not allow any of the leaves to
bind together.

All metal parts, internal and external,
are finished for high corrosion resistance.
All aluminum parts are black anodized.
Antireflection scoring and a durable
optical black are used on all surfaces
where required, internally and ex-
ternally. A high-quality baked syn-
thetic enamel is bonded to exterior

Foote and Miesse: Military-Type Lenses

221

50 'MM ftKD LONGER.
FOCAL, L.EMGTHS

25 AMD 35 MM
FOCAL LENGTHS

* A*.OOO15* E.F.L.* T MAX.
0»MtMS\OMS »M INCHES

Fig. 3. Lens and camera mounting dimensions from MIL Specification.

parts, resulting in a finishing system
that is extremely durable.

At present, the series is available in
two external enamel finishes: gray, to
match a camera on which they are
used; and black, for general service use.

All control rings are adequately
separated and are made as large as
diameter clearances permit, with broad
spaced knurls that facilitate easy manipu-
lation, even though the operator may
be wearing gloves. Focusing and iris
scales are marked in easily read charac-
ters, especially designed (for all Bell &
Howell lenses, not limited to this series)
to prevent confusion of such characters
as 3, 6 and 8, etc. The markings include
full identification of the lens, its type,
focal length in both inches and milli-
meters, filter size, sunshade thread, etc.
The iris and focusing scales are de-
signed to be read from the camera end.
The lens name and filter information

is designed to be read from the front of
the lens.

Special provision has been made to
mount standard sized filters between
sunshade and lens in a convenient recess
divided between both, so when the
sunshade is screwed in, the filter is
trapped, and protected by the sunshade
(Fig. 9). The filter can be easily
inserted regardless of the position of the
camera. If the lens is pointed down or
held on the level, the filter can be
dropped into the recess on the sunshade,
and the sunshade screwed into the lens.
If the lens is pointed up, the filter can
be dropped into the recess on the lens
mount, then trapped when the sunshade
is screwed into place. The filter sizes
are recognized industry standards (Table
I). The lens mounts have been de-
signed to use as few sizes as possible.
Four are required for this entire series:
1 using size 5, 2 using size 6, 1 using

222

September 1952 Journal of the SMPTE Vol. 59

LENS RECEPTACLES, DESA-&A CAMERA

3.3.2.10.4-

DETAIL'A" SCALE: V*r

THREAD

MIL-C-4052(U.S.A.F.)

LErtS AUGrtMEKlT KEY DETAILED *B

- LCNS LOCKIM6 Pl»4. DETAILED C
LENS SEAT LOCK.

0*Z ,1252
oo> "f-.oo\*;

(MCHES UNLESS

OTHERWISE SPECIFIED

TOLERAMCES- FRACTIONS *ooS

size 7, 3 using size 8. Thread sizes
and mount diameters have been kept
to military and ASA standards. The
sunshades have also been standardized
to these specifications and marked with
the filter size they retain.

Click stops are provided on the iris
scales to prevent accidental movement
and provide easily identified positioning.
Lenses are available in either //stops
or individually transmission-calibrated

Table I. FUters.

Size

Nomi-
nal
Size,

Max.

Max.
Thickness

No.

in.

.198

.43

.175

.634

.195

.006

.95

.219

,506

.65

.226

Foote and Miesse: Military-Type Lenses

223

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Foote and Miesse: Military-Type Lenses

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228

September 1952 Journal of the SMPTE Vol. 59

Fig. 9. The 4-in. lens, showing caps, sunshade and filter.

T stops. All scales are spread with
uniform spacing between stops. This
has been obtained by the use of a modi-
fied L-shaped iris leaf. Iris and focusing
scales either work to a common index
line, or to index lines on the same axis.
Locks have been provided to clamp the
focusing mount at any position. All
distances are measured to the focal
plane.

Two types of mount are provided.
For the 3-in. and shorter lenses, these
are the same as previously supplied,
only of a much sturdier construction,
and the focusing and iris rings have
been brought forward from the camera
for better accessability. On these
mounts, the focusing is accomplished
by rotating the focusing sleeve between
the lens and the mount on the camera.
A key in the camera keeps the lens from
rotating. The focus position is locked
by the clamp screw normally provided
on the camera.

For the 4-in. and longer lenses, an
entirely new focusing mount has been
developed, common to all three lenses.
A stainless steel adapter mounts the
entire assembly into the camera, and is
locked in position by the camera clamp-
screw. The focusing action is inde-
pendent of this. The key orients the
lens to bring focusing and iris index

fig. 10. Rear view of 2-in. and 4-in.
lenses.

marks into the operating position (Fig.
10). Stainless steel was chosen because
of its high shearing modulus and its
ability to withstand fatigue at the
junction between the camera turret and
the lens body. Further, it is electro-
lytically inert with the camera turret.
A red dot is placed on the flange focusing
seat of the adapter in direct line with
the bayonet slot, which enables the
easy mating of the slot and the bayonet
when inserting the lens into the camera.
A square aperture in the adapter
which allows added internal clearance
for the light beam to the corners of the

Foote and Miesse: Military-Type Lenses

229

-SMw

.' iv %•:
«

E H

CO S»Zir.'

230

September 1952 Journal of the SMPTE Vol. 59

frame is positioned by taking advantage
of the slot.

The focusing jacket deserves special
comment. Because of the weight of the
lenses, a sturdy mount is required
(Fig. 11). The focusing threads are
nominally square, but the sides have a
few degrees taper for ease of manu-
facturing, and to provide a good fit.
They have been perfection-lapped with
special noncharging compounds in order
to maintain smooth operation and long
life at all temperatures.

The outer sleeve is made in two
separated sections, spring loaded for
accurate positioning. The focusing
lock, when applied, operates in the same
direction as the loaded spring; thus, a
rigid, exact station of focus is acquired.
When the knurled lock ring behind the
focusing ring is turned, the floating
section of the sleeve is pushed away
from the main stationary section, clamp-
ing the threads axially on the internal
sleeve or screw.

These lenses are all flange focused
on an internal flange. Consequently,
there is no defacing of any outside
surfaces. The trimming dimension is
held within plus or minus 1/20 of 1%,
to plus or minus 1/33 of 1%, depending
on the particular focal length of the
lens in the series. Special equipment
had to be designed in order to measure
and maintain these very close dimen-
sions.

Provision has been made to add Depth
of Field Scales when required.

A new design dust cap is provided
(Table II). It is black molded cold-
resistant synthetic rubber with a metal
insert, giving the stiffness and protection
of an all-metal cap and the grip of a

Table II. Lens (Dust) Caps.

Size

No.

For Diameters

in.

1.870 47.5
2.244 57.0
2.744 69.7

rubber cap. Because of size standardi-
zation, each cap fits the lens with or
without the sunshade.

The following tabulation gives lens
nomenclature, mount characteristics, and
accessory sizes:

1-in. (25.5mm} f/2 (T2.2)

Focuses from infinity to 1 ft

Iris calibrated from//2 to //22 (T2.2 to
T22)

Filter size 6 (1$ in.)

Sunshade size 6-7

Gap size 7
1.4-in. (35mm)f/2(T2.2)

Focuses from infinity to 1.5 ft

Iris calibrated from f/2 to f/22 (T2.2 to
T22)

Filter size 5 (1 in.)

Sunshade size 5-6

Gap size 6
2-in. (50mm) f/2 (T2.2)

Focuses from infinity to 2.5 ft

Iris calibrated from f/2 to f/22 (T2.2 to
T22)

Filter size 6 (H in.)

Sunshade size 6

Gap size 6
3-in. (75mm) f/2 (T2.2)

Focuses from infinity to 5 ft

Iris calibrated from f/2 to f/22 (T2.2 to
T22)

Filter size 7 (2 in.)

Sunshade size 7

Cap size 7
4-in. (100mm) f/2 (T2.2)

Focuses from infinity to 4 ft

Iris calibrated from f/2 to f/22 (T2.2 to
T22)

Filter size 8 (2% in.)

Sunshade size 8

Cap size 8
6-in. (152mm} j I 3.5 (T3.7)

Focuses from infinity to 10 ft

Iris calibrated from//3.5 to f/22 (T3.7 to
T22)

Filter size 8 (2| in.)

Sunshade size 8

Gap size 8
10 in. (254mm) f/4.5 (T4.9)

Focuses from infinity to 25 ft

Iris calibrated from //4.5 to f/22 (T4.9
to T22)

Filter size 8 (2% in.)

Sunshade size 8

Cap size 8

Foote and Miesse: Military-Type Lenses

231

In the design of these lenses, special
engineering and manufacturing tech-
niques have been applied, which insure
concentricity. The factors contributing
most to these goals are:

7. The Optical Centering of the Elements:
Special equipment assures a high degree
of accuracy in centering before and after
cementing.

2. The Alignment of the Elements in
Their Cells: The basic geometry of the
thick edges, plus thick spacers, and the
parallel seats, assure an optical-me-
chanical self-alignment with remarkable
accuracy and without imposing im-
possible tolerances.

3. The Smooth Fit of the Threads: No
threads are generated by taps and dies.
Retaining ring threads are chased parallel
and square to the bore.

4. The Piloting of Cells and Focusing
Mounts: Where higher accuracy is re-
quired, pilots and threads are used.
The threads only to retain, and the pilots
to guide and locate. Operational
threads are lapped.

All of this is obtained without a
sacrifice to production possibilities. The
parts are held to such precision that

there is an absolute minimum of hand
fit required, which in turn insures a
production in keeping with any normal
requirements that could be placed upon
us within the realm of reason or economic
limits.

Patents have been applied for on all
of these lenses. Due to the newness of
this development, sufficient time has
not elapsed to receive patent office
action.

While being currently supplied to the
military services, it is felt that this series
contains features of value to others and
so will be commercially available.

The authors wish to give special
commendations to the staffs of both
General Scientific Corp. and Bell &
Howell Co. for the splendid help in the
design, development, testing and pro-
duction of the Miltar lenses.

Discussion

John D. Hayes (Bausch & Lomb Optical
Co.): I'd like to ask the authors how they
obtained sealing for humidity around the
iris diaphragm slot in the barrel?

Mr. Foote: There is no sealing for hu-
midity. The operational requirements of
the lens do not specify that in this par-
ticular case.

232

September 1952 Journal of the SMPTE Vol. 59

CORRECTION — PH22.1 1-1952
16Mm Motion Picture Projection Reels

IN THE PROCESS of revising Z22.ll, several drafts were considered by the
16mm and 8mm Motion Pictures Committee. In December 1949, SMPE
121 was issued containing a misplaced decimal point in the lateral runout
dimension of 200-ft reels (Table 2). Thus, the correct dimension of .057
in. was given as 0.57 in. This error was discovered only after the final
approved standard was published in the June 1952 Journal. The standard
is therefore now being republished as originally intended.

In addition, the diagram has been changed slightly to show the flanges
flat instead of flared to preclude any misunderstanding that the edges must
be rolled or flared. The words "if any" have been added at the end of the
note after "S" in the table of dimensions to make that clear.

September 1952 Journal of the SMPTE Vol.59 233

American Standard

ASA

Ktg. U. S. Pal. Off.

for

PH22. 11-1 952

Revision of

16-Millimeter Motion

Picture

Z22.II.I94I

and

Projection Reels

Z52.33-I945

*UDC 778.55

Page 1 of 4 pages

hw-

-AT PERIPHERY

Qi )

/< "N

*w-*

-AT CORE ;

j*f>

1 _

/ f "\ 1 \

ENLARGED VIEW OF HOLE N

FLANGE ON LEFT IN SECTIONAL

tf ^^^ x^ ( I

VIEW SHOW

N ABOVE

ji IGl '! ^

*-w~*

VAT SPINDLE

\ V^ 1 /

vwr

T r*~B~

T~l

iJZ

ks-|

Table 1

ENLARGED VIEW OF HOLE N
FLANGE ON RIGHT IN SECTIONAL
VIEW SHOWN ABOVE

See page 3 for notes.

Dimension

Inches

Millimeters

0319 +0.000

°'319 -0.003

8.10 +

0.00

0319 +0.000

°'319 -0.003

8.10 1;

).08

0.790 maximum

20.06 maximum

S2 (including flared,

rolled, or beveled

0.962 maximum

24.43 maximum

edges, if any)

T (adjacent to

0.027 minimum

0.69 minimum

spindle)

0.066 maximum

1.68 maximum

0.312 ±0.016

7.92 ±0.41

ftlo- +0.005

•° -o.ooo

318 +ai3
3'18 -0.00

W, at periphery3

0.66

)45
325

16<76 -a64

at core4

0.660 ±0.010

16.76 ±0.25

at spindle holes

0.660 ±0.015

16.76 ±0.38

Flange and core
concentricity5

±0.031

±0.79

Approved April 30, 1952, by the American Standards Association, Incorporated

Sponsor: Society of Motion Picture and Television Engineers

•Univerwl Decimal Classification

234

September 1952 Journal of the SMPTE Vol. 59

American Standard

ASA

Rre. V. S. Pal. Off.

for

16-Millimeter Motion Picture

PH22.1 1-1952

Projection Reels

Page 2 of 4 pages

Table 2

Capacity

Dimension

Inches

Milli-
meters

Capacity

Dimension

Inches

Milli-
meters

200 feet0
(61 meters)

D, nominal
maximum
minimum

5.000
5.031
5.000

127.00
127.79
127.00

1200 feet
(366 meters)

D, nominal
maximum
minimum

12.250
12.250
12.125*

311.15
311.15
307.98*

C, nominal
maximum
minimum

1.750
2.000*
1.750

44.45
50.80*
44.45

C, nominal
maximum
minimum

4.875
4.875
4.625*

123.83
123.83
117.48*

Lateral
runout,7
maximum

0.057

1.45

Lateral
runout,7
maximum

0.140

3.56

400 feet0
(122 meters)

D, nominal
maximum
minimum

7.000
7.031
7.000

177.80
178.59
177.80

1600 feet
(488 meters)

D, nominal
maximum
minimum

13.750
14.000*
13.750

349.25
355.60*
349.25

C, nominal
maximum
minimum

2.500
2.500
1.750*

63.50
63.50
44.45*

C, nominal
maximum
minimum

4.875
4.875
4.625*

123.83
123.83
117.48*

Lateral
runout,7
maximum

0.080

2.03

Lateral
runout,7
maximum

0.160

4.06

800 feet
(244 meters)

D, nominal
maximum
minimum

10.500
10.531
10.500

266.70
267.49
266.70

2000 feet
(6 10 meters)

D, nominal
maximum
minimum

15.000
15.031
15.000

381.00
381.79
381.00

C, nominal
maximum
minimum

4.875
4.875
4.500*

123.83
123.83
114.30*

C, nominal
maximum
minimum

4.625
4.875
4.625

117.48
123.83
117.48

Lateral
runout,7

0.120

3.05

Lateral
runout,7

0.171

4.34

maximum

*When new reels are designed or when new tools are made for present
reels, the cores and flanges should be made to conform, as closely as prac-
ticable, to the nominal values in the above table. It is hoped that in some
future revision of this standard the asterisked values may be omitted.

September 1952 Journal of the SMPTE Vol. 59

235

American Standard

Ret. V. S. Pat. Of.

for

16-Millimeter Motion Picture
Projection Reels

PH22.11-1952

Note 1: The outer surfaces of the flanges shall be flat out to a diameter
of at least 1.250 inches.

Note 2: Rivets or other fastening members shall not extend beyond the
outside surfaces of the flanges more than 1 732 inch (0.79 millimeter) and
shall not extend beyond the over-all thickness indicated by dimension S.

Note 3: Except at embossings, rolled edges, and rounded corners, the
limits shown here shall not be exceeded at the periphery of the flanges,
nor at any other distance from the center of the reel.

Note 4: If spring fingers are used to engage the edges of the film, dimen-
sion W shall be measured between the fingers when they are pressed out-
ward to the limit of their operating range.

Note 5: This concentricity is with respect to the center line of 'the hole for
the spindles.

Note 6: This reel should not be used as a take-up reel on a sound projector
unless there is special provision to keep the take-up tension within the
desirable range of 1 Vb to 5 ounces.

Note 7: Lateral runout is the maximum excursion of any point on the flange
from the intended plane of rotation of that point when the reel is rotated
on an accurate, tightly fined shaft.

236 September 1952 Journal of the SMPTE Vol. 59

American Standard
for

16-Millimeter Motion Picture
Projection Reels

ASA

Kef . V. S. Pat. Off.

PH22.11-1952

Page 4 of 4 page*

Appendix

(This Appendix is not a part of the American Standard for 16-Millimeter
Motion Picture Projection Reels, PH22. 11-1 952.)

Dimensions A and B were chosen to give sufficient clearance between the
reels and the largest spindles normally used on 16-millimeter projectors.
While some users prefer a square hole in both flanges for laboratory work,
it is recommended that such reels be obtained on special order. If both flanges
have square holes, and if the respective sides of the squares are parallel, the
reel will not be suitable for use on some spindles. This is true if the spindle
has a shoulder against which the outer flange is stopped for lateral position-
ing of the reel. But the objection does not apply if the two squares are ori-
ented so that their respective sides are at an angle.

For regular projection, however, a reel with a round hole in one flange is
generally preferred. With it the projectionist can tell at a glance whether or
not the film needs rewinding. Furthermore, this type of reel helps the pro-
jectionist place the film correctly on the projector and thread it so that the
picture is properly oriented with respect to rights and lefts.

The nominal value for W was chosen to provide proper lateral clearance
for the film, which has a maximum width of 0.630 inch. Yet the channel is
narrow enough so that the film cannot wander laterally too much as it is
coiled; if the channel is too wide, it is likely to cause loose winding and ex-
cessively large rolls. The tolerances for W vary. At the core they are least
because it is possible to control the distance fairly easily in that zone. At the
holes for the spindles they are somewhat larger to allow for slight buckling
of the flanges between the core and the holes. At the periphery the toler-
ances are still greater because it is difficult to maintain the distance with
such accuracy.

Minimum and maximum values for T, the thickness of the flanges, were
chosen to permit the use of various materials.

The opening in the corner of the square hole, to which dimensions U and
V apply, is provided for the spindles of 35-millimeter rewinds, which are
used in some laboratories.

D, the outside diameter of the flanges, was made as large as permitted
by past practice in the design of projectors, containers for the reels, rewind's,
and similar equipment. This was done so that the values of C could be made
as great as possible. Then there is less variation, throughout the projection
of a roll, in the tension to which the film is subjected by the take-up mech-
anism, especially if a constant-torque device is used. Thus it is necessary to
keep the ratio of flange diameter to core diameter as small as possible, and
also to eliminate as many small cores as possible. For the cores, rather widely
separated limits (not intended to be manufacturing tolerances) are given in
order to permit the use of current reels that are known to give satisfactory
results.

September 1952 Journal of the SMPTE Vol.59 237

72d Semiannual Convention

The Tentative Program, mailed to all members on August 29, shows the schedule
for 86 papers and Committee Reports. Sixteen Committee Meetings will be held
during the week. Of the 86 papers, 41 are for the International Symposium on
High-Speed Photography which is scheduled to begin on Wednesday morning,
October 8, with successive sessions originally scheduled through Friday forenoon.
Current developments may require Program Chairman Joe Aiken to revise this so that
the Symposium is carried through Friday afternoon. In that case, the last three
papers scheduled for Thursday afternoon at the Naval Ordnance Laboratory may
be moved to a Symposium session, and certain special motion picture papers would be
scheduled for the Naval Ordnance Laboratory Session. For the NOL Session, note
this advice repeated from the Tentative Program :

All individuals who wish to go on the trip to the Naval Ordnance Laboratory on
Thursday, must register for it prior to noon Tuesday, October 7. Those who wish to
attend this session, but who cannot register before noon Tuesday, must write their
intention to Joseph E. Aiken, 116 N. Galveston St., Arlington 3, Virginia, and state if
they are citizens of the United States.

All non-citizens of the United States must receive a special clearance for the Naval
Ordnance Laboratory visit. This may be obtained by writing to their embassy in
Washington, prior to the Convention, requesting that they be cleared for this visit to
the Chief of Naval Operations, who will in turn notify the Naval Ordnance Laboratory.

Plans for the first two days remain essentially the same as in the Advance Postal
Card Notice — Television Sessions on Monday afternoon and evening and on Tues-
day forenoon and afternoon, and a General Motion Pictures Session Tuesday evening.

Those who do not yet have hotel reservations should write Air Mail or wire Mr.
H. C. Blunck, Manager, Hotel Statler, Washington, D.C. Ask Society headquarters
for information or copies of the Tentative Program if you would like such.

Board of Governors Meeting

A major portion of the Society's Board tions and possibilities for a project control

Meeting on July 17 was a continuation and scheme that would formalize the course of

reflection of what was previously reported Society projects. These Board actions have

as "Most significant administrative develop- resulted in Proposed Bylaws,

ment of 1951 . . ." (report of this year's One proposed additional Bylaw records

first Board Meeting). This has been the the long-established underlying policy that

appointment and operation of an Execu- Standards and Recommendations de-

tive Committee. veloped by the Society are of a voluntary

From the Executive Committee's atten- nature. The other Bylaw meets the

tion to some major details and aspects of legal technicality of providing for a pro-

the Society's operation have come logically cedure for disposition of assets in case of dis-

and with minimum pain several sum- solution. These proposals were explained

mations of points of policy for the Board's in detail in the August Journal, p. 153.
consideration. The Board also reviewed

the initial outline of a study of the costs of Test Films
membership service and of the costs of

securing new members. Action was taken The Board reaffirmed the Society's

on the resignation of one Society Officer policy of developing and supplying test

and policy was carefully reviewed in regard films on a no-profit, no-loss basis. The

to another office. appropriate officers and employees were

The Executive Committee has been instructed to make whatever cost account-
studying and reviewing some legal prob- ing analyses, surveys and sales forecasts are
lems, accounting policies, test film opera- necessary to maintain the policy of supply-

238

ing test films as a part of the Society's gen-
eral program for the development of tech-
nical and engineering standards.

Membership Cost Study

The Executive Secretary presented a
brief report of progress on the Head-
quarters' cost study of membership service,
explaining that this first official attempt to
separate the Society's various operations for
the purpose of cost analysis was encourag-
ing. Comparisons were drawn between
dues paid by the average member and cost
of services rendered, and then between the
first year's dues of a new member, the cost
to secure each additional new member, and
the added cost to the Society of services
rendered to a new member during his first
year. It is expected that the completed
study will be the basis for detailed planning
of the many Society activities.

Finances and Budget

The six-month reports of the Financial
Vice-President and the Treasurer were ap-
proved. The Executive Secretary made a
preliminary report on the 1953 budget, and
the Board made recommendations as the
basis for further budget planning, so that
a proposed 1953 budget can be considered
at its next Meeting. The initial budget
planning was based on the advice of the
officers of five groups of activities: engi-
neering, conventions, publications, sustain-
ing memberships, and general membership
promotion. They were asked for their ad-
vice for 1953 compared with 1952 and the
three preceding years. Expense items
which are policy-controlled were the sub-
jects of study.

Resignation of F. T. Bow ditch

Mr. Bowditch had reported to the
Society's President on June 13 that an
emergency situation at National Carbon
Company required his attention to new
duties and his relinquishing the Society's
Engineering Vice-Presidency. The Board
regretfully accepted the resignation to be
effective October 6 and appointed Henry J.
Hood of Eastman Kodak to serve from
October 6, 1952, through December 31,
1953. Something of the scope of Mr.
Bowditch's service to the Society is given
later in this Journal under "Engineering
Activities," and in the report opening this
Journal.

Nominations and Other Reports

With one exception, the roster of nomi-
nees for the Society's 1952 election was all
cleared and was approved by the Board.

For the first time in 36 years there has
had to be a change in the nominee for
Convention Vice-President. The Nomi-
nating Committee had cause for pause:
since 1916, the Society has had "Conven-
tions by Bill Kunzmann" — so the Com-
mittee tossed into the lap of the Board the
poser created by Bill Kunzmann's forth-
coming retirement from National Carbon.
The Board discussed at great length possi-
bilities for revising the duties and lessening
the travel and other demands made on the
Convention Vice-President, but it was not
possible within the long-established policies
of the Society to work out a program that
would enable Bill to accept the nomination.
The Board, therefore, regretfully turned to
the alternative of seeking another nominee
and gave the job of finding someone to the
Executive Vice-President and a committee
of four. A number of suggestions were
received and the final choice made was
Jack Servies, Vice-President of National
Theatre Supply. The nomination of Mr.
Servies was approved by a letter ballot of
the Board and his name completed the
roster for the ballots which were mailed on
August 25 to all voting members.

Reports of the Fellow Award and other
award committees were received and ap-
proved. A complete account of awards
will be given in a later Journal. Malcolm
G. Townsley as chairman of a temporary
committee to study the method of present-
ing awards reported that his group favored
making all the presentations at the ban-
quet. An informal report from John G.
Frayne, Chairman of the 75th (Spring of
'53) Convention Planning Committee,
briefly described the program, which is to
be based on an historical theme, with the
likely extra costs for such a project being
partially offset by sales of a proposed book-
let. Important developments in motion
pictures and television over the past fifty
years would be covered in several technical
sessions, with particular papers covering
the field from the beginning to the very
latest along technical lines.

Othe/reports approved were those of the
Convention Vice-President, Editorial Vice-
President and the three Section Chairmen.

239

Engineering Activities

Engineering Vice-President

Fred Bowditch, the Society's active and
able Engineering Vice-President, has sub-
mitted his resignation, effective October
6, 1952. An increase in his responsibilities
with National Carbon Go. no longer allows
the time and attention that he feels the
Engineering Vice-Presidency requires.

Long active in the engineering and
standards work of the Society, Fred was
elected Engineering Vice-President for
1950-52 and reelected for 1952-54. The
diversity of his Society interests is indicated
in the listing below, but this in no way
begins to tell the story of the vital contri-
butions he has made to the present healthy
state of our engineering activities.

Committee Period

Color 1940-44

Inter-Society Color Council 1940-52

Papers 1941-44

Progress 1941-45

Screen Brightness 1 941

Standards, Chairman 1940-47 1941-52

Z22 (PH22), Chairman 1949-50 1946-52

Television
Board of Governors
Nominations
Fellow Award

1947-49
1949-52
1949-52
1950-52

We know that through his continued
membership on several of the above com-
mittees he will maintain his close contact
with the Society.

His successor will be Henry Hood of
Eastman Kodak. Henry started his com-
mittee activity in 1945 as a member of
the Non-Theatrical Equipment Com-
mittee. This was reorganized in 1948
as the Committee on 16mm and 8mm
Motion Pictures with Henry as chairman.
The committee blossomed under his
leadership and in 1950 he was reappointed
for a second two-year term, the maximum
permitted by the Bylaws. At the con-
clusion of his second term and in recogni-
tion of his outstanding work, he was
appointed Chairman of the Standards
Committee. At the last meeting of the
Board of Governors, July 17, Henry was
appointed to complete the remainder of
Fred's term of office. — Henry Kogel, Staff
Engineer.

Atlantic Coast Section Regional Meeting at Atlanta

The Regional Meeting of the SMPTE
Atlantic Coast Section held on Friday,
May 9, in Atlanta, Ga., as a joint endeavor
with the Atlanta Section of the IRE and
the Atlanta Chapter of the AIEE, attracted
an attendance of over 200 in the Hightower
Textile Building Auditorium of the Georgia
Institute of Technology. The arrange-
ments for the meeting were made by E. M.
Stifle, Chairman of the Atlantic Coast
Section, assisted by Charles D. Beeland and
Ben Akerman, both of Atlanta.
The program was :

Comparison of Definition in Television and
Photographic Processes by Otto H. Schade,
Tube Dept., Radio Corporation of
America, Harrison, N.J.

Eastman Color Motion Picture Films by W. T.
Hanson, Jr., Research Laboratories,
Eastman Kodak Co., Rochester 4, N.Y.

Synchro-Lite Powered 16mm Film Projector for

Television by R. E. Putnam and E. H.
Lederer, Broadcast Studio Engineering
Sec., Electronics Div., General Electric
Co., Syracuse, N.Y.

Improved Television Film Reproduction by
Vernon J. Duke and K. E. Mullenger,
National Broadcasting Co., New York,
presented by C. F. Daugherty, WSB-TV,
Atlanta, Ga.

Lighting for Television, a film, by courtesy of
CBS-TV, New York, produced by Paul
Wittig and directed by Lela Swift.
Great interest was shown in this meeting.
A number of requests have come in from
persons who attended this meeting, asking
for more similar meetings to be held in
Atlanta. In addition to the large attend-
ance from Georgia, engineers also came
from the states of Alabama, Illinois, New
Jersey, New York, South Carolina and
Tennessee. — E. M. Stifle, Eastman Kodak
Co., 342 Madison Ave., New York 17, N.Y.

240

Letters to the Editor

Re: Stereoptics Ltd. Cameras for Telecinema Film

My attention has been drawn to the
article by Mr. R. Spottiswoode which ap-
pears in the April 1952 Journal.

In order to correct any misunderstanding
which may, perhaps, have arisen in the
minds of some readers, I would like to draw
attention to the following points which Mr.
Spottiswoode — no doubt unintentionally
— has omitted to mention.

The principle of the stereo photographic
equipment, embodying two cameras, sup-
plied for the production of stereo films for
the Festival of Britain Telecinema, was de-
vised by the undersigned and the apparatus
was supplied by one of my Companies —
Messrs . Stereoptics Ltd . of London . More-
over, the principle involved is the subject of
British Complete Patent Application No.
17,086/50 which, it is understood, is due for
acceptance at an early date.

A full description of the apparatus was
given in my paper "Stereoscopy in the
Telekinema and in the Future" which I
produced last year at the request of the
British Kinematograph Society and which
was published in that Society's Journal,

British Kinematography, 18: pp. 172-181, No.
6, June 1952.

June 17, 1952 L. Dudley, Director
Stereoptics, Ltd.
Odeon Theatre
263 Kensington High St.,
London, W. 8, England

Note by Raymond Spottiswoode

One out of the four Telecinema pictures,
A Solid Explanation, was shot with the aid of
two film cameras of well-known make,
mounted on a special base incorporating
the patent Mr. Dudley refers to and de-
signed and built under his company's
direction. This film carries the credit
title, "The equipment, incorporating
cameras by Newman and Sinclair, Ltd.,
was developed by Stereoptics, Ltd."

July 12, 1952

Raymond Spottiswoode

Kingsgate

Sudbury Hill

Harrow-on-the-Hill

England

Book Reviews

Classrooms

No. 1 in a series, Planning Schools for Use of
Audio-Visual Materials. Published (1952)
by Department of Audio-Visual Instruc-
tion, National Education Association, 1201
Sixteenth St., N.W., Washington, D.C.
40 pp. 20 illus. Paper covered. 6X9
in. Price $1.00.

This is the first of a series of booklets on
planning schools for the use of audio-visual
aids.1 Devoted entirely to the planning of
classrooms for greatest efficiency, it is pre-
pared as a guide to architects and other
planners who are designing new schools or
remodeling old classrooms. Various plan-
ning groups and manufacturers of audio-
visual materials collaborated in preparing
the text.

1 D. F. Lyman, "Audio-Visual Instruction Con-
ference," Jour. SMPTE, 58: 445-449, May 1952.

The introduction states that it is gen-
erally recognized that the use of audio-
visual materials greatly enriches the child's
classroom education. Thus it prepares
him better to meet the demands of the
modern world. But it is not so well recog-
nized that school buildings must be planned
carefully by administrators, architects,
faculties, patrons and builders, or the
audio-visual program will be quite in-
effective if not impossible. The classroom
is considered in this first study because it is
the first and most important part of the
building to equip properly.

By far the chief function of the book is to
describe methods of darkening the class-
room to insure good tonal quality in the
projected picture. Several ways of darken-
ing the room are described : drapes, opaque
shades, Venetian blinds, louvres and jal-
ousies. Drawings and photographs of

241

actual installations clarify the text. Of
great practical value is the list of 36 com-
panies that produce or distribute materials
for this purpose.

One short section describes the require-
ments for adequate ventilation of the dark-
ened classroom. Other sections show the
proper ways to select, mount and use the
projection screen. There are specifica-
tions for projection stands, placement of
loudspeakers, switches, receptacles, and
conduits to connect the classroom with the
central sound and television system. A
brief section on acoustics states the funda-
mental problems simply and clearly, with
references to other authorities for more de-
tailed information.

Specifications for display facilities and
project areas for small groups emphasize
the importance of considering other audio-
visual aids. Another short section deals
with facilities for storing equipment. One
of the appealing characteristics of this
booklet is that it describes in broad terms
the general requirements for good results —
and the best methods of obtaining them —
but does not go into burdensome detail.

The final section describes the steps re-
quired to achieve the goals previously out-
lined, focusing the attention of all planners
on the activities for which provision should
be made, and getting all to support the
program. Teachers, particularly, should
be consulted. A final paragraph invites
comments from readers who need more in-
formation or have additional ideas to share
with others. A bibliography cites 26
articles and books on subjects relating to
this problem.

In view of the large number of schools
now being planned or remodeled, and in
view of the demonstrated need for a better
understanding of the requirements for
audio-visual aids, this booklet should be
given immediate, wide circulation among
those who plan classrooms. — D. F. Lyman,
Development Dept., Camera Works, East-
man Kodak Co., Rochester 4, N.Y.

Proceedings of the London Confer-
ence on Optical Instruments 1950

(Held at Imperial College, London, July
1950.) Published (1952) by John Wiley
& Sons, 440 Fourth Ave., New York 16.
i-xv + 256 pp. + 8 pp. index. 100 illus.
5 X 8 in. Price $7.00.

Kingslake reviews recent developments
in photographic lenses under high index
glasses, double-, triple- and four-element
systems, high aperture, Petzval types,
wide angle, telephoto, afocal, zoom,
catadioptric system, increased depth of
field, aspheric surfaces, mechanical im-
provements and other materials. Over
170 patents, not counting duplicates in
other countries, have issued on photo-
graphic lenses since 1940. H. H. Hopkins
discusses the zoom lenses as symmetrical
systems of variable power. Improvements
possible in high aperture lenses having
spherical fields (curved film) are discussed
by Warmisham. The remaining five-sixths
of the report covers reflecting microscopes,
gratings and their instruments, phase
microscopes, spectrophotometers, reflect-
ing telescopes, miscellaneous (velocity of
light and measurement of distance; pho-
tometry of optical instruments), and new
optical materials. This is a good summary
of the status in 1950 and gives a fairly
complete coverage in a small space. The
references provided will meet the imme-
diate need for more detail in each field.
Progress has come mainly from the newer
glasses of high index and lower dispersions
allowing the designer to use simpler con-
structions, although a few items reveal
progress from human ingenuity. — 0. W.
Richards, American Optical Company,
Stamford, Conn.

Technical Optics (Vol. II)

By L. C. Martin. Published (1950) by
Pitman, 2 W. 45 St., New York 19. 327
pp. + 12 pp. appendix + 4 pp. index.
Approx. 260 illus. 5| X 8^ in. Price

$7.50.

Like most books on technical optics
this volume follows the regular pattern,
having one chapter on single lenses and
magnifiers followed by a chapter each for
telescopes, magnifiers, photographic lenses,
and the testing of optical instruments.
In each chapter the historical development
is followed by some of the technical ques-
tions encountered in the design of optical
instruments.

Related topics are the subject of chapters
on binocular vision and binocular instru-
ments, photometry (where projection sys-
tems and projectors are briefly described),

242

and aspheric surfaces. In the latter
chapter, Schmidt systems and other recent
high-speed aspheric systems which are of
interest to the projection of television
images are discussed. In four appendixes,
symbols, defraction gratings, chromatic
abberation of thin lenses, and data on
seven photographic lenses are given.

The publisher states, "the book is of the
greatest value to scientific instrument
makers, ophthalmic opticians, spectacle
makers, and students." The technical
descriptions and derivations do not make
this book easy to read for the casual
reader but rather a book for the student
and scientific user of optical instruments.
Even though it can serve as a useful ref-
erence or study book of technical optics
it cannot be classified as a treatise on the
subject. A great majority of the references
are to British works and authors, and little
mention is made of work done in other
countries.

Engineers and physicists dealing with
the design of optical instruments will
find this book a valuable addition to their
library. Other American readers who
want an insight into this branch will,
no doubt, prefer Fundamentals of Optical
Engineering by D. H. Jacobs, or The
Principles of Optics by A. G. Hardy and
F. H. Perrin. — Dr. John L. Maultbesch,
Vice-President, Kollmorgen Optical Corp.,
347 King St., Northampton, Mass.

Focal Cine books

A special series of inexpensive, popular
monographs on motion picture subjects,
consisting of the following :
How to Script, by Oswell Blakeston, 1st ed.,

1949

How to Film, by G. Wain, 3d ed., 1952
How to Direct, by Tony Rose, 1st ed., 1949
How to Edit, by H. Baddeley, 1st ed., 1951

How to Act, by Tony Rose and Martin

Benson, 1st ed., 1951
How to Process, by Leslie J. Wheeler, 1st ed.,

1950

How to Title, by L. F. Minter, 1st ed., 1949
How to Project, by Norman Jenkins, 2d ed.,

1951
How to Cartoon, by John Halas and Bob

Privett, 1st ed., 1951
How to Use 9.5mm, by D. M. Neale, 1st ed.,

1951

Published by Focal Press Ltd., 31
Fitzroy Sq., London, W. 1, England.
Paper bound. Price 7s. 6d.

This series of popular monographs is,
in a sense, the motion picture counterpart
to Focal Press' famous series of basic
booklets in still photography. However,
for the "still" series the titles were char-
acterized by the two-word prefix "All
About" instead of "How to," as in the
present series. The general level of the
motion picture booklets is considerably
more advanced than that established for
the still booklets; nevertheless, by no
stretch of the imagination can the motion
picture booklets be recommended to the
specialist, except possibly to the extent
that a specialist in one field might find
the booklets on subjects outside his re-
spective field worth reading. For example,
a director or film editor could derive some
insight into the complexities of processing
by a reading of How to Process. But he
would gain a false impression of modern
motion picture laboratory practice if he
went no further, for the booklet treats
the subject entirely from a standpoint of
home processing on old-fashioned drums.

The booklets generally are well written
and thoroughly illustrated. They are
obviously directed to the serious amateur
who wants to improve his film results and
dabble in home laboratory procedures. —
Lloyd E. Varden, Pavelle Color, Inc., 533
W. 57 St., New York 19, N.Y.

SMPTE Officers and Committees: The roster of Society Officers and the
Committee Chairmen and Members were published in the April Journal.

243

Positions Wanted

TV Producer-Director: Now Chief of Production in Army's first mobile TV system;
military experience in writing-directing high-speed, low-cost instructional productions;
formerly TV producer-director, KRON-TV San Francisco, five shows weekly; will be
separated from service Nov. 1952; desire connection in educational TV, preferably em-
ploying kinescope techniques; married; prefer West Coast, but willing to travel; resume,
script samples, pictures of work — on request; 1st Lt. Robert Lownsbery, SigC Mbl TV
Sys, c/o Sig Photo Center, 35-11 35th Ave., Long Island City 1, N.Y.

Journals Available and Wanted

Available

Upon a reasonable offer to Alfred S. Norbury, 3526 Harrison St., Kansas City 3, Mo.:
Vol. 44 (Jan.-June 1945) Vol. 50 (Jan.-June 1948)

Vol. 45 (July-Dec. 1945) Vol. 51 (July-Dec. 1948)

Vol. 47 guly-Dec. 1946) Vol. 52 (Jan.-June 1949)

Vol. 48 (Jan.-June 1947) Vol. 56 (Jan.-June 1951)

Vol. 49 (July-Dec. 1947) Vol. 57 (July-Dec. 1951)

A set of Journals from January 1945 through 1951 at SI 5. 00 plus packing and carrying
costs from Richard W. Maedler, 32-52 — 46 St., Long Island City 3, N.Y.

Complete set, in excellent condition, from January 1930 to date, plus one issue of Sep.
tember 1928 from Don Canady, 5125 Myerdale Drive, R.R. 15, Cincinnati, 36, Ohio.

5 years (1947-51) in perfect condition plus the indexes for 1936-45 and 1946-50 and
including the 1949 High-Speed Photography, upon any reasonable offer to Vic Gretz-
inger, 3547 Suter St., Oakland 19, Calif.

Transactions Nos. 11, 14, 20, 21, 23, 25, 27, 28 and 38; and 22 years of the Journal (1930-
1951) except for Jan., Feb., Mar. and Apr. of 1934, Jan. and Apr. of 1948, and Feb. 1950;
also these extra single copies — Nov. 1930; Jan., Feb., July and Nov. 1931 ; June 1932;
Mar. and Apr. 1933; Dec. 1934; Jan. and May 1935; Oct. 1938; July and Dec. 1940;
Oct. 1948 and Jan. 1950, upon any reasonable offer made to Paul J. Larsen, Assistant to
the President, Borg-Warner Corp., 310 So. Michigan Ave., Chicago 4, 111.

Wanted

Transactions 1, 6 and 7. Contact Mrs. Dorothy Gelatt, Henry M. Lester, 101 Park Ave.,
New York 17, N.Y.

High-Speed Photography, Volume 7, reprint or original Journal, March 1949, Part II, by
John H. Waddell, Wollensak Optical Co., 850 Hudson Ave., Rochester 21, N.Y.

244

New Members

The following members have been added to the Society's rolls since those last published. The
designations of grades are the same as those used in the 1952 MEMBERSHIP DIRECTORY.

Honorary (H)

Fellow (F)

Active (M)

Associate (A)

Student (S)

Barker, Lovell H., Film Processing Laboratory

Owner. Mail: 9208 Memorial, Detroit 28,

Mich. (M)
Bernstein, Paul, TV Studio Technician and

Engineer, WOI-TV, Iowa State College,

Ames, Iowa. (A)
Blanchard, Vernon W., Chemist, E. I. Du Pont

de Nemours & Co., Photo Products Dept.

Mail: 42 South Drive, Lawrence Brook

Manor, Rt. 9, New Brunswick, N.J. (A)
Bostwick, James W., Manager, Motion Pictures

& Slide Films, General Motors Photographic,

General Motors Corp., B-120 GM Bldg.,

Detroit 2, Mich. (M)
Brasier, C. S., Scientific Photographer, Ministry

of Supply, British Government. Mail: 4

Romney Rd., Southcourt, Aylesbury, Bucks,

England. (A)
Carter, Bryan, Chief Electrician, Universal

Pictures Co., Universal City, Calif. (M)
Chessman, Walter E., Jr., Mechanical Engineer,

Alexander Film Co. Mail: 1516 Vista PL,

Colorado Springs, Col. (A)
Coan, Edward M., Television Engineer, Allen

B. DuMont Laboratories, Inc. Mail: 37

Overlook Rd., Cedar Grove, N.J. (M)
Cook, George R., Treasurer, Radio Station

WLS. Mail: 1419 Lathrop Ave., River

Forest, 111. (M)

Cotcher, Alfred L., Electronic Scientist, Na-
tional Bureau of Standards. Mail: 3410

Highview Ct., Wheaton, Md. (A)
Dobbs, Frank S., Manufacturer, Cine Products

Supply Corp., Ashland, N.J. (M)
Drucker, Donald, Motion Picture Film Editor,

Charles R. Sene. Mail: 6804—18 Ave.,

Brooklyn, N.Y. (A)
Faithorn, Nathaniel R., Television Engineer,

The Associated Broadcasters, Inc. Mail:

430 Myra Way, San Francisco 16, Calif.

(A)
Filmer, Philip, General Manager, General

Motors Photographic, General Motors Corp.,

407 General Motors Research Bldg., Detroit,

Mich. (M)
Green, Phil C., Television Engineer, WSM

Television. Mail: 4112 Rockdale Ave.,

Nashville, Tenn. (A)

Hewins, Leonard J., Manager, Mole-Richard-
son (Spain). Mail: Garcia Morato 121,

Madrid, Spain. (M)
Huffman, Robert L., Mechanical Engineer,

Automatic Electric Co. Mail: 1033 W.

Van Buren St., Chicago 7, 111. (A)
Karo, James, Photographic Supervisor, Sandia

Corp. Mail: 1123 Silver Ave., S.W.,

Albuquerque, N.M. (A)

Keller, John S., Supervisor, Field Optical
Installations, Sandia Corp. Mail: San
Felipe Lodge, Apt. 201, Sal ton Sea Base,
Westmorland, Calif. (M)

Koch, William A., Chemist, Eastman Kodak
Co., 342 Madison Ave., New York 17, N.Y.
(M)

Lenz, Irvin W., High-Speed Motion Picture
Camera Technician, Sandia Corp., Field
Test Dept., Sandia Base, Albuquerque, N.M.
(A)

Macauley, Alan C., 16mm Production and Dis-
tribution, World Films. Mail: Box 72,
Sierra Madre, Calif. (A)

Marcus, Paul, Chief Engineer, Partner, Bell
Recording Co., 112 W. 89 St., New York
24, N.Y. (A)

Matt, Richard J., Producer, Box 581, Fond du
Lac, Wis. (M)

McNaughten, Neal, Director of Engineering,
National Association of Radio and Television
Broadcasters, 1771 "N" St., N.W., Wash-
ington 6, D.C. (M)

Moore, Charles S., Supervisor of Sound Engi-
neers, Radio Corporation of America. Mail:
6703 Starling Cir., Dallas, Tex. (A)

Pendreigh, Harold A., Projectionist, J. Kelly
and R. Pannett. Mail: 88 George St.,
Rockhampton, Queensland, Australia. (A)

Peterson, Harry, Cinematographer, Atlas Film
Corp. Mail: 411 Marion St., N., Oak Park,
111. (M)

Rafalon, Jules, Mechanical Engineer, Assistant
Chief, Pathe Laboratories, Inc., 105 E. 106
St., New York 29, N. Y. (M)

Read, Edmond C., Jr., Kinescope Recording
Engineer, National Broadcasting Co. Mail:
4038 Michael Ave., Venice, Calif. (M)

Reiter, Samuel S., New York University. Mail:
1937 E. 37 St., Brooklyn 34, N.Y. (S)

Richardson, Robert W., Motion Picture Writer,
Photographer and Producer, Barber-Greene
Co., 400 Highland Ave., Aurora, 111. (M)

Rowe, Thomas L., Chief Engineer, Radio
Station WLS. Mail: 2324 W. Lunt, Chicago
45, 111. (M)

Ruberg, Elden E., Sound Technician, Radio
Corporation of America. Mail: 1039 Hart-
zell St., Pacific Palisades, Los Angeles, Calif.
(A)

Strauch, Frederic P., Jr., Sales Engineer, Bell &
Howell Co. Mail: 1122 Dartmouth, Wil-
mette, 111. (A)

Wilner, John, Director of Engineering, Hearst
Corp., 2610 N. Charles St., Baltimore 18,
Md. (A)

245

Wilson, Ralph J., Supervisor, Photo Section,
Sandia Corp. Mail: 295 C St., Brawley,
Calif. (A)

Winkler, Edward A., Chemical Engineer,
Eastman Kodak Co., 342 Madison Ave.,
New York 17, N.Y. (M)

Wolf, George E., Assistant Production Manager,
Murphy-Lillis Productions, Inc. Mail: 3
Glenwood St., Little Neck, L.I., N.Y. (A)

Wood, Donald M., In Charge of Research
Photography, Bendix Aviation Corp. Mail:
10410 E. Jefferson, Detroit 14, Mich. (A)

Zaccardi, Sgt. Carmie M., Motion Picture

Photographer, U.S. Air Force, Box 494, Hq.

AFFTC, Edwards Air Force Base, Edwards,

Calif. (A)
Zost, Elmer G., Chemist, Alexander Film Co.,

Alexander Film Bldg., Colorado Springs, Col.

(A)

CHANGES IN GRADE
Drew, R. O., (A) to (M)
Foster, John C., (A) to (M)
Gawel, Eugene W., (S) to (A)
Paramasivaiah, P., (S) to (A)

Current Literature

The Editors present for convenient reference a list of articles dealing with subjects cognate
to motion picture engineering published in a number of selected journals. Photostatic
or microfilm copies of articles in magazines that are available may be obtained from The
Library of Congress, Washington, D.C., or from the New York Public Library, New
York, N.Y., at prevailing rates.

American Cinematographer

vol. 33, June 1952
Economy Set Lighting With Gone Lights

(p. 248)

Camera Heater for Cold-weather Filming
(p. 250) R. Lawton

vol. 33, July 1952

Stereo Movies Without Spectacles (p. 295)

A. D. Roe

Filters in Cinematography (p. 296) /. Forbes
Electronic-Photo Recording — New TV

Filming Method (p. 298) C. L. Anderson

Bild und Ton

vol. 5, May 1952
Die transportable Riffelwand (p. 150) G.

Hoffmann
Warum zerspringen Stufenlinsen? (p. 136)

H. Jent&ch
Mikrofotografie im Dienste der Kreislauf-

forschung (p. 139) G. Vogel

British Kinematography

vol. 20, May 1952

Problems of Storing Film for Archive Pur-
poses (p. 150) H. G. Brown

Electronic Engineering

vol. 24, July 1952

Some Converter Tubes and Their Applica-
tions (p. 302) /. A. Jenkins and R. A.
Chippendale

A Method of Measuring Television Picture
Detail (p. 308) G. G. Gouriet

Electronics

vol. 25, June 1952

Pack-Carried Television Station (p. 98)
L. E. Flory, W. S. Pike, J. E. Dilley and
J. Af. M organ

Self-Focusing Picture Tube (p. 107) A. T.
Bentley, K. A. Hoagland and H. W. Gross-
bohlin

Kino-Technik

no. 5, May 1952
Deutsche Ausfuhr von Kino-Film rollt

langsam an (p. 101)
Geiselgasteig ist fur den Farbfilm geriistet

(p. 102)
Das Bild der deutschen Filmwirtschaft —

gestern und heute (p. 105) A. N, Narath
Welche Anforderungen stellt das Fernsehen

an den Rohfilm? (p. 114)
Storungen bei der Vorfuhrung von Farb-

filmen (p. 117) K. Braune and H. Tummel
no. 6, June 1952

Welche Anforderungen stellt das Fernsehen

an den Rohfilm? (p. 149)
Storungen bei der Vorfiihrung von Farb-

filmen (p. 151) K. Braune and H. Tilmme

Radio & Television News

vol. 47, June 1952

(Radio-Electronic Engineering Section)
What's Ahead for Small-Town Television?

(p. 31) N. Sklarewitz

Radio & Television News

vol. 48, July 1952
Improved Intercarrier Sound System (p.

36) W. H. Buchsbaum
Unique Magnetic-Tape Applications (p.

38) L. A. Wortman
Pulses in Sound Reproduction (p. 59) G.

Southworth

Tele-Tech

vol. 11, Aug. 1952
Eidophor Projector for Theatre TV (p. 1 12)

246

New Products

Movie Sound 8 is the first commercially
available equipment for recording and
reproducing magnetic sound on 8mm film.
The equipment comes in a single case,
including a built-in 6-in. speaker and a
microphone, and is marketed at $398.50
by Movie Mite Corp., 1105 Truman Rd.,
Kansas City 6, Mo. Magnetic striping
of 8mm film is now available at 3^ a foot
from Reeves Sounder aft Corp., 10 E.
52 St., New York 22, N.Y.

Movie Mite Corp. felt that an entirely
new projector should be designed to get
sound successfully on 8mm, chiefly to
overcome wow and flutter problems and
to provide 24 frame/sec sound speed and
also the old, silent speed. To avoid
sprocket hole modulation, a system called

the Roto-Magnetic Stabilizer was de-
veloped to allow scanning the film in a
flat plane. The use of a slightly tapered
sound drum provides a substantial amount
of the edge guiding needed. There are
only two sprockets. They are driven by
a worm gear connected by a rubber belt
to the motor.

The standard projector has two input
positions — for the record player and for
the microphone. A small mixer is avail-
able for the operator who wishes to record
from two records and a microphone. It
is not necessary to use special film stock.
Old 8mm films as well as new can be given
the 25-mil magnetic stripe which is placed
outside the perforations.

247

New electronic humidity controls are de-
scribed in .Bulletin F-5173 recently issued
by Barber-Colman Co., Rockford, 111. It
is called two-position and proportioning for
process or comfort control. It is a plug-in
element designed for wide range with simple
adjustments. In spaces supplied by a cen-
tral fan, the sensing element is mounted
either in the duct or the conditioned space,
remote from the amplifier and adjustments.
For controlling humidity in spaces not com-
pletely air conditioned, the control is avail-
able with the operating adjustment mech-
anism mounted in a cabinet.

Nema Movie Guide — 1952 is a com-
pilation of complete data on "16mm Elec-
trical Films." The Guide covers 409 films
giving running time, color, sales or rental
prices, release dates when ascertainable,
sources (producer or chief distributor, with
other possibilities covered in an extensive
index of producers and distributors), and
grading of films when that was obtainable,
with keys for: guide or manual; primary;
elementary; junior high school; senior

high school; college; trade school and
trade; and adult education. A 6-page
"Classification by Subjects" makes this
Guide very useful. It should be noted
that there is only one film distributed by
NEMA — Installing Armored Cable. All the
other 408 films must be ordered from the
sources listed. The Nema Movie Guide is
available from the National Electrical
Manufacturers Association, 155 E. 44 St.,
New York 17, N.Y.

Meetings

72d Semiannual Convention of the SMPTE, Oct. 6-10, Hotel Statler,

Washington, D. C.

Other Societies

National Electronics Conference. Annual Meeting, Sept. 29-Oct. 1, Sherman Hotel,

Chicago, 111.

Optical Society of America, Oct. 9-11, Hotel Statler, Boston, Mass.

American Institute of Electrical Engineers, Fall General Meeting, Oct. 13-17, New

Orleans, La.

American Physical Society, Oct. 17-18, Cornell University, Ithaca, New York
Acoustical Society of America, Nov. 13-15, Balboa Park, San Diego, Calif.
American Standards Association, Annual Meeting, Nov. 19, Waldorf-Astoria, New York
American Physical Society, Nov. 28-29, Washington University, St. Louis, Mo.
American Institute of Chemical Engineers, Annual Meeting, Dec. 7-10, Cleveland, Ohio
Institute of Radio Engineers Conference and Electronics Show, 5th Annual Southwestern

Conference and Show, Feb. 5-7, San Antonio, Texas

248

Basic Principles of the
Three-Dimensional Film

By RAYMOND SPOTTISWOODE, N. L. SPOTTISWOODE and
CHARLES SMITH

Professional three-dimensional (3-D) film productions cannot be satisfactorily
undertaken without a comprehensive theory of the transmission of an image
in space from scene to screen. In Part I the outlines of such a theory are
laid down, and the elements of a standard set of concepts and nomenclature
put forward. Part II draws an example from a recent film, The Black Swan, to
show how the stereotechnician computes a sequence of shots in the desired
space relationship, and how simple graphical techniques may be employed to
plot such relationships. From these graphs may be determined the magnitude
of any postcorrections required to alter the continuity in space, to adjust
the film to screens of widely differing size or to eliminate certain camera
errors. Part III forms a critique of existing camera procedures, including
those based on the supposed identity between human vision and the viewing
of the space image. Part IV sums up the differences of technique between
the flat film and the 3-D film.

p TO NOW the production of three-
dimensional (3-D) films has been spo-
radic — scattered all over the world and
separated by long intervals of time.
Most of the practical information avail-
able was to be found in papers by the
American pioneer, J. A. Norling, which
were read before the Society;1 but these
dated from before World War II and
applied to films of rather limited scope.

A contribution submitted July 21, 1952, by
Raymond Spottiswoode, N. L. Spottis-
woode and Charles Smith, Stereo Tech-
niques, Ltd., 36, Soho Square, London,
W.I., England. This article is an adap-
tation of part of the forthcoming book, The
Theory of Stereoscopic Transmission.*

More recently in England, the Festival of
Britain afforded an opportunity to pro-
duce a varied program of stereoscopic
films; these too have been described in
outline in the Journal.2'3 Production did
not stop at this point, however, for a fur-
ther series of films was initiated for com-
mercial distribution starting in the early
summer of 1952. Both these programs
were based on the same body of technical
principles: both were the work of the
same groups, one in Canada for the ani-
mation films, the other in Britain for the
studio and actuality films. By the com-
pletion of the second program, therefore,
with an output of about a dozen films,
much production experience had been

October 1952 Journal of the SMPTE Vol. 59

249

gained and knowledge accumulated on
the ways in which audiences see and react
to this new kind of film. The present
paper is an attempt to summarize a part
of this knowledge in the hope that it may
be of value to American producers who
are experimenting in the 3-D medium.
To make the theoretical part of the treat-
ment more concrete, we relate it in an
extended example to a particular film
completed a few months ago.

A 3-D Ballet Film

The presentation of our Festival pro-
gram at the Telecinema drew many re-
quests for a stereoscopic ballet — a sub-
ject notoriously difficult to film satis-
factorily in the ordinary way. We
therefore decided to produce a ballet
film for 1952, even though time did not
allow of special choreography to take
fullest advantage of the dimension of
depth. Our final choice fell on an epi-
sode from Tschaikovsky's Swan Lake,
which made a story complete in itself
within the limits of 13 minutes of film,
and enabled us to feature two of the star
dancers of the Sadlers Wells and Covent
Garden companies, Beryl Grey and John
Field.

Shooting was to be limited to four days
on the studio floor, and this meant careful
preplanning of stereoscopic effects in rela-
tion to the script. For this purpose it
was essential to know how the dancers
were to move in relation to the move-
ments of the camera, which was to be
mounted on a crane in the interests of
complete fluidity. There was, however,
a formidable problem to contend with

which has no counterpart in the making
of ordinary films : namely, to control the
position in space in the ultimate movie
theater of each scene occurring in space
before the camera. The continuity
might demand a smooth spatial transi-
tion between one shot and the next; or
there might have to be an abrupt impact
of something presented much nearer to
the eye or much farther away than the
audience would expect. Examples of
both types of "continuity in space"
abound in this film. Again, from shot
to shot it would be necessary to adjust
the camera to the precise range of dis-
tances in the scene before it; and if any
errors occurred at this stage, it must be
possible to determine and correct them
by optical printing. Finally, in thel
interests of strain-free viewing, it was
essential to be able to take into account
all those factors which affect the fusion
of the images, and whose neglect in the
past has often led to eye fatigue and has
tended to give 3-D films a bad name
among the public.

There is no way of achieving thisj
assured control over the image through-
out its progress to the movie theater ex-
cept by having at one's command a com-
plete knowledge of the stereo transmis-
sion system between camera and specta-
tor. Fortunately, long before the shoot-
ing of The Black Swan was attempted,
such a transmission theory had been
worked out, and a full account of it will
shortly be available to American readers.4
Nonetheless, some attempt must be made]
here to indicate the nature of the pro
lems and the lines along which they ca
be solved.

PART I: THEORY

As is well known, all commercial
stereoscopic film systems of today are of
a type which may be called piano-stereo-
scopic: that is, the constituent optical
images from which the depth image is
formed by binocular fusion are projected
on a surface, the screen. In large-screen

projection, these optical images a
superimposed, and must be sorted out byj
each spectator with the aid of individual!
viewing devices, which are normally of!
polarizing material. It is thus necessarw
to start with an analysis of the way tha
spectator sees' the picture in space, after!

250

October 1952 Journal of the SMPTE Vol. 59

which we can work back through the pro-
jection and production processes to the
camera which is to be controlled on the
studio floor.

Psychological Viewing Factors

In the spectator's mind two altogether
different sets of impulses are at work.
The binocular faculty attempts to place
objects in space by methods which are
still imperfectly understood in their en-
tirety, but which may for simplicity be
likened to the working of a rangefinder.
At the same time, other departments of
the mind are busy observing all sorts of
other clues to depth and position in space.
There may well arise conditions when
these two sets of data will conflict, lead-
ing to an ambiguity in the image which
different people will resolve differently —
much as two people may sit down before
a Picasso canvas in the Museum of
Modern Art and come to wholly differ-
ent conclusions as to what it is all about.
Even more serious difficulties will arise
if the conflict is so fundamental that the
spectator cannot bring himself to believe
in the stereoscopic data. A scene may
be brought forward to a certain plane in
space, but will not in fact appear to be
there because the audience cannot accept
the fact that a dining room table or a
ballet dancer is poised in space over the
front rows of the stalls. This effect has
been known for many years, and is well
analyzed in a classic paper by Professor
J. T.

T
does

The planning of our stereoscopic films
of course take account of these and
many other psychological factors; and
hope, if interest in the 3-D film con-
active, to discuss in a later paper a
mber of new ways of bridging the re-
maining gap between audience and space
film. In the present paper we shall con-
fine ourselves to considering the physical
elements in the stereoscopic transmission
system, since these have been the subject
of much fruitless debate, which it is time
to try and replace with an agreed nomen-

clature and method of mathematical
approach.

The Mechanics of Viewing

The elements of a piano-stereoscopic
projection system, with image separation
at the spectators' eyes, are sketched in
Fig. 1. A generalized spectator is
shown, placed at a distance, V, from the
screen, onto which have been thrown
left- and right-eye images. It is con-
venient to consider these images as con-
sisting of a multitude of separate points,
much as is often done in discussions of
film resolving power. In general, to
each point on the left-eye image there
will be some corresponding point in the
right-eye image, both image points hav-
ing the characteristic that they represent
the same object point in the original
scene.* These image points are some-
times called homologous points, and they
are represented in Fig. 1 by L and .ft.f

The eyes are shown as having a sepa-
ration, t, this letter also being used in our
nomenclature to denote the lateral sepa-
ration of optical axes, suitable subscripts
being used to distinguish the camera and
projector. Through their selecting
viewers, the eyes regard separately the
left and right members of each pair of
homologous points on the screen, whose
horizontal separation is known as paral-
lax. Parallaxes are always denoted by

* Note that the original object may be
imaginary, as in 3-D abstract and cartoon
films.

f It is noteworthy that, in a projection sys-
tem such as we are discussing, the eyes are
able to prompt the mind without any addi-
tional clues as to which pairs of points are
to be considered homologous; occasional
errors — as in the fusion of wire mesh and
wallpaper patterns — occur also in bin-
ocular vision and are of negligible impor-
tance in practice. On the other hand,
some types of integral screen, which dis-
pense with viewers for seeing 3-D films, re-
quire the transmission of information as to
which points are homologous, and are
therefore "information-consuming" and
wasteful.

Spottiswoode, Spottiswoode and Smith: 3-D Photography

251

Screen

L and R are homologous
image points delivered
at screen by projector(s).

Image-selecting
viewers

Fig. 1. Construction of a space image point (/) from
optical image points, L and R. A spectator's eyes, EL,
ER, having a lateral separation, t, are equipped with
selecting viewers and regard, respectively, left and right
corresponding image points, L and R. These are separated
on the screen by a parallax, zs, which may be positive or
negative. The spectator, distant Ffrom the screen, will see
the fused image point, 7, at the intersection of the rays from
EL to L, and ER to R. His distance from / is denoted by P.

the letter z, a subscript being added to
distinguish the kind of parallax referred
to. Thus a screen parallax is zs, a paral-
lax on the projected film zp, a parallax
introduced by displacement in the optical
printer zd, and a parallax originating in
the camera zc.

Three special cases are shown in Fig. 1 ;
(a) that in which zs = t, for which rays
of light are reflected parallel from the
screen, so that the image point is placed
at infinity; (b) that in which zt = 0, in

which the point is imaged in the plai
of the screen (whence it follows that a
normal flat film is merely a special case
of the 3-D film, that in which zs = 0 for
all image points) ; and (c) that in which
zg = —t, and the image, as may be seen
from simple geometry, is halfway out to
the spectator.

From previous theoretical discussion,
the impression has got around that stereo-
scopic projection is extremely compli-
cated, requiring special and often vari-

252

October 1952 Journal of the SMPTE Vol. 59

able alignment of the projectors, and an
analysis of keystone distortion, optimum
lens focal length, and so forth. Projec-
tors, however, are much better regarded
as fixed mechanisms, which cannot be
swiveled or otherwise adjusted from shot
to shot. Furthermore, image distortion
arising from projection is no more ob-
jectionable in a 3-D than in a flat film,
and can safely be relegated to the back-
ground as a second-order problem,* pro-
vided that no additional distortion is
caused by beam-splitting or other
methods.

Hence it is only necessary to agree on
the parallax at the screen between the
left-eye image, regarded as a whole, and
the right-eye image regarded as a whole.
The alignment which we have adopted is
that which differs least from the standard
alignment of projectors for flat films,
namely, one in which the image center-
lines are superimposed. This can be
succinctly expressed as ZCL = 0. Some
consequences of altering the value of
ZCL are discussed later in this paper.

With t, the spectator's eye separation,
substantially constant at 2.5 in., and with
zCL assumed equal to zero, only two pro-
jection factors need to be considered:
F, the spectator's distance from the
screen, and Af, the linear magnification
which the image undergoes from film to
screen.

The Nearness Factor

Referring again to Fig. 1, we can now
advance to the first useful generalized
concept, which appears not to have been
remarked on before, though it is essential
to any clear discussion of the production
of 3-D films. It may be stated quite
generally that, for any pair of optical image
points, the ratio of the spectator's viewing dis-
tance (V) from the screen to his distance (P)

* Projector separation, tp, inevitably pro-
duces some second-order distortion due to
keystoning. This is analyzed fully in Ref-
erence 4, together with some attendant
anomalies of vision which help to rectify
the shape of the image.

from the fused image point is a constant, no
matter whereabouts in the theater he may be
sitting.

This ratio we call the nearness factor
(N) of the image point, and we may
therefore write,

-p-N (1)

It is apparent that,

if P = oo, N = 0 (image at infinity),

if p = vt N = 1 (image at the screen
plane),

if P = ;r> N = 2 (image halfway out
to spectator), and
so on.

We can therefore state unambiguously
for the first time where we wish a certain
object in a studio set or on location to ap-
pear in space to the spectator in the
movie theater.* If the director says that
he wishes an actor seated at a table to be
represented at N = 0.5, while another's
hand, outstretched toward the audience,
is to be at N = 4, the stereotechnician
knows at once that each spectator is to see
the first actor at twice the viewing dis-
tance to the screen, whereas the other's
hand must come out from the screen
three-quarters of the way toward him.
The concept of the nearness factor is
easily grasped, even by studio personnel
to whom the rest of the stereo shooting
procedure remains something of a mys-

* In 1856, Sir David Brewster, writing
about the wire mesh and wallpaper phe-
nomena mentioned above, gave numerical
data from which the constancy of N with
change of viewing distance can be cor-
rectly inferred. 6 But he failed to generalize
the concept of the nearness factor, no doubt
because of his preoccupation with the prob-
lems of individual viewing. (It must be
remembered that, prior to the invention of
the incandescent lamp, only very rudimen-
tary means were available for projection to
large audiences.) Nonetheless, Brewster
was far ahead of his time, and his book is
even now worth reading.

Spottiswoode. Spottiswoode and Smith: 3-D Photography

253

tery; but it affords the connection of
ideas most necessary to establish between
director and stereotechnician.

Object Distances and Image Distances

Next we must see how the position of
the camera in front of the scene is related
to the image of that scene in front of the
spectator. Denoting by dn the distance
from the camera to a given object point,
there will be a corresponding image point
seen by a spectator in the theater as hav-
ing a nearness factor, Nn. Specifically,
we may refer to an image point at No
(infinity) deriving from an object point
at do, an image point at NI deriving from
a point at d\, and so on.

Now if we were to graph the distance
of object points do, d\, d% . . . against the
actual distance, P, of the corresponding
image points from the spectator, it must
not be supposed that the result would
necessarily be a straight line. This
represents an important but entirely spe-
cial type of stereoscopic transmission;
that is to say, one in which the rendering
of distance is a linear function. We shall
meet this again later on, but it is worth
observing here that linear transmission
does not of itself produce an orthostereo-
scopic image, or one which is geometri-
cally congruent with the original scene.
There may be a multiplying factor either
greater or less than unity by which a
given length is stretched or shrunk,
though of course uniformly throughout
the scene.

A New Unit: The Rho

We now come to the problem of relat-
ing do, di, d-i ... in the scene to -/V0, NI,
JV2 ... in the theater. Here another im-
portant step forward has been taken in
the simplification of stereo calculations
by introducing a new unit of distance.
It can be shown that if a reciprocal dis-
tance unit is employed, equal numbers of depth
units in the scene will always correspond with
equal changes of nearness factor in the cinema,
no matter whether the transmission system is
linear or nonlinear.

Thus at one stroke a mass of difficult
computation is done away with, and
depth ranges in the scene can be manipu-
lated by simple arithmetical addition and
subtraction.

The new distance unit has been named
a rho ("reciprocal" denoted by the Greek
letter p), and to bring it to a convenient
size it is defined as the reciprocal of the
distance in inches multiplied by an arbi-
trary constant, the p constant (K), which
has been set at 6,000. Thus we may
write

distance in p =

6,000*

distance in in.

(2)

This is equivalent to 500 divided by dis-
tance in feet, and the units of course de-
crease with increasing distance, and vice
versa, as is shown in Table I.

Table I

Distance

100ft

6ft

100

4ft

6 in.

111

120

125

150

167

Whereas distances in linear units are
expressed as do, d\, d2 . . ., the correspond-
ing p distances are designated DO, D\,
D% . . . . All measurements on the set
and on location are made with a tape
graduated in p on one side and in feet and
inches on the other, for focusing. (In
passing, it is worth noting that if lens-
focus scales were engraved in p, they
would be calibrated with equal sepa-
rations for equal p differences, in place of
the present unequally divided scales.
Furthermore, depth of focus tables would
need only one entry under each focal

* Because of the superior convenience of a
decimal system of linear units, we have re-
cently converted to the metric system.
1 metric p = 10,000 /distance in cm.

254

October 1952 Journal of the SMPTE Vol. 59

length and aperture setting, instead of a
multitude of entries relating to all pos-
sible focus distances. But to gain these
worth-while advantages, camera assist-
ants would have to train their minds to
udge distances nonlinearly, which would
no doubt prove difficult !)

In order to indicate how the general
equation is derived, which connects the

distance of objects in the scene with the
distance of their corresponding images in
the cinema from the spectator, it is neces-
sary to return for a moment to the cinema
and re-examine the parallaxes on the
screen (zs). Referring again to Fig. 1,
and adopting the sign convention that
uncrossed parallaxes are positive and
crossed parallaxes negative, we can see
at once that

when zs = t, P = F/0, i.e., image at NQ (infinity)

zs = 0, P = V/\, i.e., image at N\ (plane of screen)

zs = — t, P = F/2, i.e., image at N% (halfway out)

zs = -2t, P = F/3, i.e., image at N3 (f of way out)

Zg = — 3t,P = V/4, i.e., image at N^ (f of way out), and so on.

Note: In our standard terminology, the letter t always represents the lateral distance
between two optical axes, t itself denoting the separation of the human eyes (here assumed
throughout as 2.5 in.), te the separation of the camera optical axes, tp that of the projector
optical axes, etc.

In other words, equal negative incre-
ments of parallax produce equal in-
creases in N value. Moreover, these
parallaxes are absolute; that is to say,
they derive only from factors which are
constant for any observer sitting in a
given position in the cinema. They are
irrespective of the size of the screen.
But the corresponding parallaxes on the
projected film, zp, are related to the
screen parallaxes, zs, by an optical mag-
nification, Af, which will be greater or
smaller according as the screen is wider
or less wide. Stated the other way
round, a parallax of given magnitude on
film will produce a greater or lesser
stereoscopic depth according as the
screen is larger or smaller. This impor-
tant influence of screen size was first
clearly stated, and its effects remarked
on, by Professor Rule in the paper al-
ready cited.

Depth Content in the Theater

At this stage it will help to introduce
another concept, that of the depth content
of the film in the cinema ; in other words,
the range of depth in space which the
image occupies. Let us assume a differ-
ence in nearness factor of 2 between the

front and rear planes of the image, which
we shall express as *N%. Normally the
range of N values would be from NQ
(infinity) to Ar2, but from the point of
view of the parallax analysis which fol-
lows, the position of the N range in space
is immaterial. For example, A-/V2 might
correspond to the range N\-N^ as in the
recent McLaren cartoon film, Twirligig.
Now it is apparent from what has been
said that

zs
M

(3)

Since a change in N value of 1 results
from a change of screen parallax of /, a
depth content of ^N\ corresponds to a
parallax on the projected film of 2.5/M
in., a depth content of AjV2 to 5/M in.,
and so on.

Magnitude of Film Parallaxes

In order to give a more concrete idea of
the magnitude of the actual film paral-
laxes when shooting for screens of normal
commercial size, it may be helpful to de-
viate for a moment from the main course
of the argument. Table II has been
prepared to show the total span of film
parallaxes available (in mils) for films

Spottiswoode, Spottiswoode and Smith: 3-D Photography

255

256

October 1952 Journal of the SMPTE Vol. 59

Table II

Table III

Magnifi- Screen
cation Width

(Af)* (WO

Total projected film
parallax, zp (mils) for

Minimum values of zp
(mils) for SN = 0.1

200 13ft9in. 12.5 25.0 37.5

250 17 2 10.0 20.0 30.0

300 20 8 8.3 16.7 25.0

350 24 1 7.1 14.3 21.4

400 27 6 6.25 12.5 18.75

* Based on the standard 35-mm projector
aperture width, 0.825 in.

employing depth contents of AJVi, AjV2
and AA^3. The *N\ column is of interest
merely because there remain some con-
servative spirits in the 3-D film field who
think that no action should take place in
front of the screen plane.

In realizing a given depth content in
the cinema, there is however another
factor to consider. The representation
of a given depth space may be imagined
as built up of an infinite number of infi-
nitely thin planes. Were this achiev-
able, we might say that the stereoscopic
resolving power was infinite, for the system
would have an infinite capacity to dis-
criminate depth. In actual practice,
however, these planes will be replaced by
more or less shallow zones, within each of
which a position in depth will not be
accurately reproducible. The depth of
the zones will therefore be a measure of
the stereoscopic resolving power of the
system. These zonal depths may con-
veniently be denoted by the change in
nearness factor, bN, which they repre-
sent, and we accordingly employ the con-
cept of dN to clarify discussions of resolv-
ing power, without suggesting that this
will necessarily be the unit finally
accepted.*

Assume, then, that any volume of space
denoted by A7Vi is to be representable in
10 zones of depth; in other words, dN

* Experiments are being undertaken with
trained observers to determine whether
8N, dP or perhaps some other concept corre-
sponds best with the subjective impression
of depth resolution.

200

1.25

(250
<300
(350

1.00)
0.83>
0.71 J

400

0.63

Note: The bracketed range comprises
approximately 67% of existing motion
picture theaters, as revealed in the recent
SMPTE survey.7

= 0.1. We can then tabulate the mini-
mum film parallaxes which it will be
necessary to have recorded reproducibly
on the projected film — that is, after tak-
ing into account all possible random par-
allactic errors in previous stages of the
transmission system.

Table III shows that, for screens found
in the majority of commercial theaters,
the minimum reproducible film paral-
laxes needed to achieve a depth resolving
power of 0.1 do not much exceed the di-
mensional tolerances of the film itself, let
alone allowing for shrinkages which may
occur at intermediate stages in commer-
cial laboratory practice, or for mechani-
cal errors in the stereoscopic adjustments
of the camera. The need for extreme
precision is still further emphasized by
the fact that 8N = 0.1 is equivalent to
only 20 separable zones in space for a
normal 3-D film having a depth content

The General Equation

Reverting to our main theme, it will
be evident that the greater the magni-
fication, M, the greater the screen paral-
lax to be derived from a given film paral-
lax. Turning to the camera, it can be
seen from Fig. 2 that an object point at a
given distance produces a greater film
parallax, (a) the longer is the focal
length, fc, of the camera lens(es), and
(b) the greater is the lateral separation,
tc, of the lenses or optical systems. Thus
an increase in these three factors, Af, fe

Spottiswoode, Spottiswoode and Smith: 3-D Photography

257

and tc, increases the final parallax on the
screen, whose absolute magnitude deter-
mines the N value of the image point
corresponding to the original object
point, 0. In fact the product Mfctc is
combined into what is called the C factor
in our general equation.

This equation, which will be stated
but not derived here, expresses the dis-
tance, P, of a fused image point from the
spectator in terms of the distance, p, from
the camera of the original object point,
together with the other variables of the
transmission system.

(4)

Thus, besides M , fc, tc and p, which we
have already mentioned, there is an A
factor and a B factor. * The A factor, Vt,
is a function of the spectator and his view-
ing distance from the screen, as may be
seen from Fig. 1 . The B factor denotes
an important transmission concept,
which is governed by the convergence of
the camera optical axes (or its preferable
equivalent, inward lateral displacement
of the lenses relative to the films).

The B factor can be related to a
camera convergence half-angle, <p, and
a projector convergence half-angle, 6, as
follows, taking account of the fact that
an optical printing displacement, zd,
may have been introduced between the
camera film and the projected film:

B = tp - t

+ 2M(fc tan <p - fp tan 0 + zd} (5)

If lens displacement is employed in-
stead of toe-in in the camera, h, and pro-
jector, H, we may write instead,

B = tp - t + 2M(h - H + Zd) (5a)

As a transmission factor, B may be
very much more simply defined. Let
mzt denote the screen parallax of a point
which was at infinity in the scene, i.e.
at DQ. Then

B = °>z. - t (6)

Expressed in words, B is the excess of
screen parallax of a point originally at

infinity over the separation of the human
eyes.

B+, B = 0 and B— Transmission

Three important cases now arise : that
in which B is positive, that in which it is
zero, and that in which it is negative.
The discussion of the three types of
stereoscopic transmission system will help
to clear up the vexed question of camera
convergence, a subject on which much
ink has been spilt in the effort to estab-
lish as fundamental relationships what
have been only rough-and-ready rules.
Several of these are now being purveyed
by inventors in France, Germany and
Holland, but on investigation they are
found to be merely crude approxi-
mations, the errors in which may be
masked by the fact that they have been
applied only to films projected on very
small screens.

Figure 3 shows in graphical form the
principal characteristics of B-+-, B = 0
and B— transmission systems. It is to
be noticed that both axes are scaled in a
reciprocal type of unit, the x-axis in terms
of D, and the ^-axis in terms of N.
Hence the origin represents infinity on
both axes. From Eq. (6) it will be seen
that when B = 0, mzs = /. When, as
here, the screen parallax of a point equals
the eye separation, /, rays reaching the
eyes will be parallel, as they are when re-
flected from points at infinity. In other
words, infinity in the scene (see definition
of °°2-g) appears at infinity in the cinema.
Thus a B = 0 shot must be represented
in Fig. 3 by a line passing through the
origin, and no other type of shot can be
so represented. Referring again to Eq.
(6), if °°zs exceeds t, it must be that some
point short of infinity in the scene pro-
duces on the screen a parallax equal to /
(because a point at infinity produces a
parallax greater than t). Thus, when B
is positive, a point nearer than infinity
in the scene will correspond on the screen
with a point which tends to appear at
infinity. On the other hand, if "z, falls
short of /, so that B is negative, it must

258

October 1952 Journal of the SMPTE Vol. 59

N,
Image 3/4 way out to spectator 4

3.5
Image 2/3 way out to spectator 3
2.5
Image 1/2 way out to spectator 2
1.5

Image at plane of screen 1

/
/

/
0.5
/
/

Image at «, / Q

B- B-0 B = 0 B=0 B-f-

/ J

D = 0/
N>0/

1
1
|

/Xr>=o

I^N=0

/tan-

c/t

Region of negative fi
D and N values /J
1 ' '

(High C value)
•« A£ —
(Medium C value

, Ar

/ D > 0 (Distances in reciprocal units)
1 N = 0

le)

(Low C vah

Fig. 3. The three types of stereoscopic transmission system: #+, 5 = 0 and B — .

be that a point situated at infinity in the
scene will appear at some nearer distance
in the cinema. All examples of stereo-
scopic transmission (in other words, all

Class

B = 0
B+

B-

instances of 3-D recording and repro-
duction) must fall into one of these three
classes, whose main characteristics may
be exhibited thus:

Name Characteristic

Ortho-infinite Linear; infinity points correctly represented.

Hyper-infinite Nonlinear ; objects short of infinity represented at

infinity.
Hypo-infinite Nonlinear; objects at infinity represented closer

than infinity; cardboarding.

In the example of a B — system shown
in Fig. 3, it will be noticed that infinity
(i.e. D = 0) will appear on the screen
plane, that is, at N\. This will occur, for
example, if a shot of distant objects is
taken with the camera axes parallel (<p =
0), and projected with the projector axes
toed-in so that the parallax of the aper-

ture centerlines is zero (ZCL = 0). This
frequently happens with amateur pro-
jection of stereoscopic stills and
movies.

In short, the B factor can be varied at
three stages in the production process,
either angularly or by displacement, as
follows :

Spottiswoode, Spottiswoode and Smith: 3-D Photography

259

By By

toe-in displacement

In the camera <p h

By optical printing zd

By projection 6 H

For ease of calculation, it is better to
reduce all the stages to a displacement,
using equivalences derived from Eqs. (5)
and (5a). This also makes it possible to
employ the simple graphical techniques
of shot analysis described in Part II of
this paper. Note that the effects of con-
vergence and displacement (apart from
second-order distortions in the case of
convergence) are fully accounted for by
the B factor alone. There is no problem
of camera or projector axis alignment
which cannot be very simply solved by
the methods described here.

Depth Range in the Scene

Figure 3 illustrates another important
idea, that of the depth range of a scene,
which is defined as the range of dis-
tances corresponding to a given depth
content in the cinema. The symbol A is
used to denote a difference of D values,
so that, for example, AI signifies a range of
reciprocal distances which will produce
a depth content of AJVi in the cinema
under given transmission conditions.
AI may of course designate Z>i — DQ or
D2 — DI, and so on, as with its equiva-
lent in the cinema, *Ni. It will be
noticed from Fig. 3 that the depth range
may be obtained from the depth content,
or vice versa, by simple reflection through
the appropriate characteristic curve,
which will always be a straight line, no
matter whether the transmission is linear
or nonlinear.

These curves are based on the funda-
mental equation connecting reciprocal
distances in the scene with nearness fac-
tors in the cinema. It is derived from
Eq. (4) and can conveniently be written,

(7)

Hence the characteristic curves of Fig.
3 make an angle with the *-axis equal to

tan

sloping more steeply therefore as the C
factor increases. We have already seen
that an increase in the C factor increases
the film and the screen parallax of a
given object point in the scene. Hence it
will also increase the depth content,
AAf, in the cinema for a given span of
depth range, A, in the scene. Or, to put
this in a form more useful to the camera-
man, the larger the C factor, the shal-
lower will be the depth range in the scene
for any given range of N values in the
cinema. This is clearly shown in Fig. 3
by the family of curves representing a
5=0 shot.

It can be shown algebraically that the
depth range, A, is independent of the
value and sign of the B factor, so that,
for any transmission characteristic what-
soever, we may write

Djf - Do = — (8)

whence D2 — DQ = —^
C

and

(8a)

(8b)

where D is expressed in p and K is the p
constant, 6,000.

Finally, combining Eqs. (8a) and
(8b), we may write

Dl =

(8c)

This furnishes us with the necessary
relationships between all the significant
distances in the scene. It remains only
to show how DI determines the conver-
gence or effective convergence of the
camera axes.

If the camera axes are toed-in on a
point at a certain distance, the film paral-
lax, zc, of this point will be zero. If,
then, the images are projected on a screen
with ZCL = 0, the point will appear on
the plane of the screen, i.e. at N\.
Hence the original distance of the point
was DI. In other words, when ZCL = 0,

260

October 1952 Journal of the SMPTE Vol. 59

Fig. 4. Front side of the Stereomeasure (built in 1950), a calculator for

relating D, A, M, fc> tc, cot <p and md for all shooting conditions

likely to be encountered in the studio and on location.

the point on which the camera axes are
converged is distant D\ from the camera.
The half-angle of convergence being
denoted by </?, it is evident that

,
tan- -,

(9)

where tc is in inches, and D\ in p. In
terms of d\, the distance in inches from
the camera to the point of convergence,
we may write

-i tc

<f> = tan

(9;

If, which is preferable, each optical
system is laterally displaced inward
through a distance, h, in relation to the
film, we may write instead,

Or, expressed in terms of d\t

, fete

h = o~7
2d\

(10)

(lOa)

We suggest that h (and its projection
counterpart, H} be denoted by the term
edge-in to differentiate it from physi-
cal convergence of camera and projector
axes which is often conveniently de-
scribed as toe-in.

The Stereomeasure

With the aid of the reciprocal distance
system and Eq. (8) and its variants, an
experienced stereotechnician can make
all the necessary depth range and depth
content calculations in his head, finally
obtaining the values of <p or h from simple
tables. However, as an aid to memory,
these relationships and others have been
embodied in a calculator, the Stereo-
measure, which was designed and built in
1950 and has since been used for every
one of our productions. One side of
this calculator is shown in Fig. 4. It
gives immediate numerical answers to all
problems of how the camera should be
set up to produce the effect in space de-

Spottiswoode, Spottiswoode and Smith: 3-D Photography

261

manded by the director, whether this be
intended to soothe or startle, and whether
the continuity from shot to shot be a
matching or a deliberate mismatching of
planes. Recently, with the aid of metric
units and other simplifications, it has
proved possible to design a much more
compact version of the Stereomeasure
which contains the same information but
lends itself to quantity production.

So far we have been concerned with
the space relationships obtaining between
a scene existing in real space and the
same scene as reconstructed in stereo-
scopic space by a binocular spectator sit-
ting in the motion picture theater; and
we have seen how these two quite differ-
ent types of space can be related to one
another by adopting new systems of
measurement and comparison.

Stereoscopic Magnification

The next step is to examine how the
size and shape of objects are affected by
their stereoscopic transmission and repro-
duction. It is well known that a monoc-
ular image is essentially ambiguous, for
the data it contains can (in the absence
of other evidence) be construed by the
spectator's mind as presenting a small
object at a near distance or a much larger
object farther away. By contrast, a bin-
ocular image — on the basis of the
stereoscopic data it contains — is entirely
unambiguous; it is determinate in size,
shape and position. But these char-
acteristics do not necessarily conform
with those of the object represented;
its image in space may be larger or
smaller, widened or elongated, nearer or
farther away. These distortions are cer-
tain to arise when presenting pictures on
large screens; but whether they are ob-
jectionable or not depends on a great
many factors, some stereoscopic, some
extra-stereoscopic, and some psychologi-
cal, which will vary greatly from one
spectator to another. Nonetheless, it is
important to be able to determine mathe-
matically what distortions the image has
undergone, and this .must form an inte-

gral partof the whole transmission theory,
just as much as an analysis of waveform
distortion forms part of the theory of elec-
tronic amplification.

Considering the stereo image of an
object in the real world, we may call the
ratio of the stereoscopic image size to the
real object size the stereoscopic magnifica-
tion, which may of course be greater
or less than unity. It can be shown that
the depth of objects may undergo one
type of magnification (called depth mag-
nification, md), while the height and
width of objects — dimensions between
which a piano-stereoscopic transmission
system does not discriminate — undergo
another type of magnification, called
width magnification, mw.

Stereoscopic magnification varies,
among other things, with the size and
sign of the B factor. In the general case,
in which B 7^ 0, we may write, for any
given plane in the image having a near-
ness factor, N,

Vt /B

Mfct\Nt

+ 1

(11)

When .5 = 0, the expression in
brackets equals unity, and the equation
reduces to

Mfctc

It can also be shown that, in the same
general case in which B ^ 0, the width
magnification for an image plane having
a nearness factor, N, is given by

When

0, this reduces to

(12)

(12a)

Finally, since it is often the shape of
objects which is more important to their
acceptability than their absolute mag-
nification along any dimension, it is
helpful to introduce the concept of the
shape ratio, /*. Then

262

October 1952 Journal of the SMPTE Vol. 59

M = ^ = -£-(£ + l) (13)

Since Eqs. (11)-(13) involve the B
factor, it is convenient to have an expres-
sion by which this factor can be easily
reckoned when working out numerical
examples. It is assumed that C and DI
are known, as they will be when shooting
conditions have been established. Then,

B - 67M, - ' (14)

where /c, tc and t are measured in inches,
and DI in p. If d\ (in in.) is employed
in place of D\, this expression becomes,

B = -d -t (14a)

The Orthostereoscopic Condition

This is the condition of perfect image
reproduction — i.e. that in which the
image as a whole is geometrically con-
gruent with the scene it represents. So
many inventors have claimed a system
which produces a distortion-free image
that it is worth investigating just what
orthostereoscopy entails. For linear re-
production it is necessary to have B = 0,
and for geometrical congruence md =
mw = 1, so that /z = 1. Substituting
mw = 1 in Eq. (12a), we have tc = t.
Putting tc = t and md = 1 in Eq. (lla),
we have V = Mfc. Thus the three con-
ditions for geometrical congruence are:

B = 0

tc = t

V = Mfc

(15)

If the focal length of the camera lens
and the screen size have been deter-
mined, the spectator's viewing distance
is fixed. Furthermore, for a normal
space film having a depth content of A2, it
can be shown that, under orthostereo-
scopic conditions.

12,000

(16)

when the rear of the scene is at Do.

For example, if M = 300 (i.e. a 20 ft
8 in. screen), and if/c = 2 in., the near-
est object to the camera must not be
closer than 20p, i.e. 25 ft. Thus no
shooting system can claim to eliminate
distortion which does not comply with
all the conditions of Eq. (15); and no
system which complies with these con-
ditions can claim to be practical for com-
mercial films, since it would be limited
to the taking of long shots. Hence it
may safely be asserted (notwithstanding
many statements to the contrary), that
distortions are inseparable from stereo
films — as indeed they are from flat
films — and that it is therefore necessary
to study their character and incidence.

In Part II of this paper are to be found
numerical examples which demonstrate
very clearly the type of distortion to
which a stereoscopic system is prone,
especially when large B values are em-
ployed. It is the depth of objects which
tends to be most exaggerated, because of
the squared term in Eq. (11); as the
scene recedes, so it rapidly becomes more
elongated. Experience confirms the ill
effect caused by very large values of B,
but it would appear that objects in the
foreground and middle distance are the
worst sufferers, perhaps because the eyes
normally look downward on them more
than on distant objects, so that one is
more often reminded of their shape.

Binocular Magnification

There is however another kind of mag-
nification to which the stereoscopic
image is subject. Stereoscopic depth
magnification is based on the supposition
of a slight depth shift, dp, in the object
position, which is then compared with the
corresponding shift in the image position,
dP. In other words,

a concept which corresponds to that of a
one-eyed spectator with a .foot-rule at
the camera and in the theater — al-
though, of course, in the theater he would

Spottiswoode, Spottiswoode and Smith: 3-D Photography

263

need two eyes in order to construct the
depth image at all. Now if a two-eyed
observer were stationed at the camera
position, the front plane of a given object
in the scene would subtend some angle,
w, at his two eyes, and the back plane of
the same objecc a smaller angle, a/. If
co — o}' were not too small an angle for
the eyes to discriminate, the object would
appear stereoscopically solid. Now sup-
pose this object to be imaged and trans-
mitted to a theater under given con-
ditions. For a spectator of known posi-
tion and characteristics, the same object
will subtend at its front plane an angle 12,
and at its rear plane an angle, 12'. The
ratio of a small change in the image
angle, 12, to a small change in the object
angle, co, may be called the binocular mag-
nification, mb, and an expression may be
found for it which is analogous to those
enunciated above in Eqs. (11) and (12).

do)

(17)

Note that mb is purely a form of depth
magnification, having no relation to the
width of the image, that it is independent
of the value of B, and that (were the two

kinds of magnification found to be multi-
plicative in effect), when B = 0, md =
\/mb. Their inverse operation has im-
portant practical consequences which
will be discussed in Part II.

The Complete Theory

This short outline of fundamental prin-
ciples can of course be developed very
much further, and its fuller implications
are set out in the work already cited.*
These shed light on fascinating possi-
bilities of set design which take advan-
tage of the image distortions we have
noted, just as the set designer of today
makes fullest use of the potentialities of
linear perspective. They help to ana-
lyze many new techniques in cell and
puppet animation. They enable the
camera designer to lay down parameters
for the construction of professional stereo
film cameras. They enable a producer
to undertake a complicated studio pic-
ture in the confidence that all the prob-
lems along the way — titles, optical
effects, back projection, stereo windows,
and so on — can be surmounted with a
full knowledge of what is being done.

PART II: PRACTICE

It may be that a transmission theory
such as this, containing as it must many
new terms and concepts, will at first seem
difficult to grasp, and perhaps too ab-
stract for the practical needs of film
makers. Yet just these objections were
made when sensitometry was first intro-
duced as a science. It was puzzling to
have to think of densities and gammas
and toe exposures when a mere twist of a
lens diaphragm had previously seemed
to suffice; yet today all these and many
other terms are so much a matter of in-
stinct that they trip off the technician's
tongue with scarcely a second thought.
The practice and nomenclature evolved
here for the 3-D film have been carefully
worked out with the needs of the pro-
fessional film maker in mind. Very soon

he is just as happy with depth ranges and
nearness factors as he is with the rest of
the science of film, because he can see
what these things mean as soon as he
starts to make his first stereoscopic movie.

Within the limits of this part of the
paper, we shall try to make the reader
feel that he is sharing in the production
of a section of The Black Swan, one of the
many films now completed in accord-
ance with this technique. We shall
show how the stereoscopic constants are
computed, how film parallax is after-
wards determined, how camera errors, if
present, may be corrected, and how the
image in space finally appears to a mem-
ber of the audience.

The camera on which this film was to
be shot consists of the twin assemblv de-

264

October 1952 Journal of the SMPTE Vol. 59

Fig. 5. 3-D camera mounted on crane during filming of The Black Swan.

picted in Figs. 5 and 6, this being the only
equipment presently available in Eng-
land for double-band 35mm shooting.
As can be seen from the nearer view
(Fig. 6), two Newman-Sinclair cameras
are mounted on a stereoscopic base,
shooting into mirrors set at 90° to one
another, and having their apex facing
the scene.8 This arrangement provides
for convergence by physically toeing the
cameras inward, and it enables tc to be
varied from a maximum of 8 in. to a
minimum of 1.25 in. (2.5 in. with the 35-
mm lenses). To set against this usefully
wide variation, the camera has manifold
disadvantages, chief of which are that a
nonstandard image geometry results
from reversal at the mirror surfaces, and
that inaccuracies of setting due to faulty
construction are so serious and unpre-
dictable that a special optical printing
technique has had to be devised to correct
them.

The first of the two shots we are going
to consider in detail depicts the Male
Variation danced by John Field. He
finishes with a held pose which, in the
stage version of the ballet, enables the
audience to applaud. As a counterpart
to this, the director, Len Reeve, proposed
a stereoscopic curtain effect, making use
of a pair of decorative banners which
were to be raised before the scene at the
end of the first shot, quite close to the
audience's eyes. The immediate cut to
the next shot would reveal a similar pair
of banners at a slightly greater distance,
hiding the scene ; and as these were raised
out of sight, another pair behind them
would be revealed, only to rise in favor
of a third, and so on until Beryl Grey was
discovered at the back of the set begin-
ning her variation.

Always when making a 3-D film the
director will search for visual material
which will enhance the sense of forward

Spottiswoode, Spottiswoode and Smith: 3-D Photography

265

Fig. 6. Front view of 3-D camera showing Newman-Sinclair units in opposed
positions and 90° mirrors. Matched lens pairs are available in the normal range
from 35mm to 100mm, with coupled focusing; a centrally mounted Mitchell-type
viewfinder is used for monitoring.

and backward movement, of nearer and
farther away. In unskilled hands this
may easily degenerate into a trick, a
mere device for showing off the third
dimension to the best advantage. But
the imaginative director will find that
all kinds of new visual ideas will present
themselves, which would be ineffective in
the ordinary flat film, or which take on a

new vitality in the more real world of
3-D. The transition we are discussing
proved very successful because the totally
unexpected appearance of the banners
caused the audience's attention to move
rapidly into the extreme foreground, this
being followed by the smooth withdrawal
of attention to the back of the next scene,
the time occupied being sufficient to

266

October 1952 Journal of the SMPTE Vol. 59

Fig. 7. Slate 15 of The Black Swan. Camera out of picture on left, banners
raised successively in pairs to reveal Beryl Grey in background.

cover the musical transition and hide the
break which was intended for stage
applause.

Computing the Stereo Settings

The simple mechanics of this shot are
shown in Fig. 7. But how is the stereo-
technician on the set to ensure that the
director's wishes as to the placing of the
scene in space in the ultimate movie
theater are precisely carried out? First
it is necessary to decide the size of screen
for which the film is to be shot, since this

will determine Af, the one element in the
C factor which is not controllable when
shooting. If the anticipated variation of
screen width is not very great, it is best
to set M for the largest screen size, and
accept some loss of depth on smaller
screens. But if a wide range of screen
sizes must be provided for, it is better to
find a mean magnification so that the
loss on the smallest screen is not too great,
while accepting some divergence on in-
finity points on the large screens unless
these are corrected in an optical printing

Spottiswoode, Spottiswoode and Smith: 3-D Photography

267

stage.* The Black Swan was to be pre-
sented for 22 weeks on a screen only 10
ft 4 in. in width (M = 150), and this sug-
gested shooting it for a 1 5-ft screen (M =
218), since it was known that results on
even a 20-ft screen would then be entirely
acceptable.

Accordingly, the Stereo measure was
permanently set at M = 218, this being
analogous to the choice of a film emul-
sion for a production, which gives rise to
a fixed speed setting on the exposure
meter. While the movement of the
camera on its crane was being rehearsed,
distance measurements were taken from
it to the dancer and to different parts of
the set. These measurements were made
with the special Stereotape graduated in
p on one side and linear units (for focus-
ing) on the other.

For the first shot, the entry in the
stereotechnician's log begins as follows:

Slate 35: LS Prince (John Field), who
dances his Variation. Rear of set at
10p. During the dance, camera tracks
in, and the Prince finishes in MLS at
33p. At end of dance, as Prince
kneels, banners rise in front of him,
covering whole frame, at 65p from
camera. For continuity with follow-
ing shot (already taken), banners
should be at or around #2.75.

It should first be determined whether
this shot can be made with B = 0, i.e.
with linear transmission, placing DQ at
Op. Since the banners are to appear at
-#2.75, the depth range is A2.75. The
cameraman having selected a 35mm
lens (fc = 1.38 in.), it can readily be de-
termined by Eq. (8), or from the Stereo-
measure, that tc = 2.1 in. However,

* The excessive positive zs resulting from
projection with too large a value of M. can
be corrected by supplying a negative correc-
tion of suitable size which will alter B and
increase the N value of the nearest planes.
This can be done by projecting with ZCL
negative, but better by optical correction.
Note that N factors will be increased both
by the larger M and by the extra negative
screen parallax.

this value of tc is not obtainable on our
camera with the 35mm lens, and the
shot must therefore be recalculated for
B-\-. The simplest procedure is as fol-
lows.

Taking the minimum setting of tc (i.e.
2.5 in.), we then have M, fc and /c, and
therefore the C factor. The most distant
plane in the set, 10p (i.e. 50 ft), is set at
infinity, DQ. The Stereomeasure, solv-
ing Eq. (8) directly, gives 30p as the value
of Z>i, and shows that the banners
will in fact appear at A^.ya.

Hence the stereotechnician's entry con-
cludes,

Treat shot as B+, with fc = 35mm,
tc — 2.5 in., and cot ^ = 160. Dl to
be at 30p. Nearness factor of raised
banners works out at JV2.75, as desired.

These measurements and calculator
readings occupy only a couple of min-
utes, and in a few moments more the
camera is set to tc = 2.5 in. and cot p =
160, the latter value having been ob-
tained from scales on the Stereomeasure
which relate tc and D\, as in Eq. (9).

Two further points deserve comment.
Firstly, what could have been done if the
proposed settings had placed the banners
in the wrong plane in theater space?
Had they proved too far away, it would
have been possible (a) to reduce the dis-
tance in the studio between camera and
banners, (b) to increase /c, or (c) to in-
crease te. Both (a) and (b) alter the
composition of the shot, and so (c) is
usually the preferable alternative. Had
the banners proved to have too great a
nearness factor, it would have been neces-
sary to resort to the inverse procedure of
(a) or (b), since the tc setting was already
a minimum; This points to the need of
incorporating the lowest practicable mini-
mum tc in the design of the camera.

Secondly, it may be asked what effect
on the appearance of the shot is likely to
result from changing B = 0 to B-\-.
Setting the rearmost plane at Do should
of course place it at infinity, and clever
set design will in fact produce a very

268

October 1952 Journal of the SMPTE Vol. 59

marked elongation, an advantage when
designing spectacular scenes. The back-
grounds of normal interior sets are not
likely, however, to suffer any appreciable
deformation. It is the foregrounds, es-
pecially when they contain objects of
familiar shape, which may be more vis-
ibly distorted. An example of a visible
kind of stereo distortion is worked out
from the data on the following shot.
Practice, and frequent viewing of 3-D
films, will tell the stereotechnician what
is acceptable and what is not. It is un.
likely, however, that he will satisfy every-
one; for reasons that are not yet clear,
people differ enormously in their sensi-
tivity to stereoscopic shape and size.

When the stereo settings have been
made, one more step is required to be
taken before the camera is ready to roll.
This is the Stereo test, which provides the
necessary data under the microscope to
determine the actual, as contrasted with
the nominal, values of cot <p (or h) and
tc. To make this test, a small target
board resembling a ping-pong bat is run
out first to a distance of 40 p and then to
22 p with the aid of the Stereotape, a few
frames of film being exposed at each dis-
tance. The lens focus is set at 15 ft for
both shots, since the lens-to-film distance
enters into the equations, and must there-
fore remain constant.

The shot which follows Slate 35 in the
film had already been taken. It was the
nearness of its front banner which had to
be exceeded in 35, in order to produce
the desired progression in space. The
entry in the stereocontinuity book is as
follows :

Slate 15: Shot opens with pair of ban-
ners in CS, filling screen, at 79p (6 ft
4 in.). Banners raised out of picture
to reveal further pair, and so on, till
raising of 4th pair reveals Odile
(Beryl Grey) in LS, who starts to
dance her Variation. Camera static,
rear of set at 13p (39 ft). At end of
slate, Odile has danced into MS at 48p
(10 ft 5 in.).

Treat shot as 5 + , with/c = 50 mm,
tc = 1.25 in. and cot <f> = 220. Thus
Do = 13p, D! = 44p, and D2 = 75p,
since AI = 31 p. Hence front banner
is slightly closer than N2, actually

#2.13.

The method of working out this shot
need not be repeated here, since it re-
sembles the previous example and can be
checked with the help of the equations
already given. Although the stereotech-
nician will seldom have to force the
cameraman's hand in the choice of lenses,
or the director's in the arrangement of a
scene, he is nevertheless bound to be con-
stantly preoccupied with the smallest
value of tc which his equipment will pro-
vide. In studio work, with its large
depth ranges, he is likely to be pressing
against this limit much of the time. In
Slate 15, for example, 1.25 in. was the
absolute minimum tc available with the
50-mm lens, and had it been desired to
hold the nearest banner farther away
than NZ.I, while retaining it at the same
field size, nothing could have been done
— except by allowing divergence to
occur in the farthest planes of the shot.

Image Distortion in the Theater

The data already provided for Slate 1 5
makes another interesting analysis pos-
sible ; by studying the shape of different
parts of the image, it is possible to get a
clearer idea of the distortions set up in the
motion picture theater. Let us consider
the plane in the image corresponding to
Beryl Grey's position when she has
danced forward at the end of the shot,
and is at 48 p. The spectator is assumed
to be at a distance from the screen of
2.5W.

Example: It is required to find the
depth magnification, width magnifica-
tion and shape ratio for Slate 15 at a
plane in the scene distant 48p from the
camera, when the spectator is seated
at 2. 5 W from the screen for which the
film was shot.

Spottiswoode, Spottiswoode and Smith: 3-D Photography

269

Object

distance

in rhos

:.,

Sign co

+ V€
— Vt

Project

nvention:
parallax
parallax
on: ZCL =

uncro
cross
0

ssed
id

60 S

hot as on
inal nega
'actual)
\

Banners

on|

S/ >

',' /

Shot

as plannpd

/ / /

anted)

s ,

N -ve:

\ ^'

Shot as obtained

diverger

ice

s\f

'correcte

Zr ' in mils

)

+30

+25

+20

+ 15

-rlO

+ 5 0

-5

-10| -15

-20

-25

N factors at M . 218 i W = 15 ft) -^ NO NI N2 N3

Fig. 8. Graphical analysis of Slate 35 of The Black Swan, showing relation between

object distances in scene and nearness factors in cinema, together with

method of postcorrection of convergence errors by optical printing.

Object
distance
in rhos

80 / XT,-

~ Front
banners

(N2.85)

/Front /t

I7 banners//

' ?$£

Sign convention:
+ve parallax uncros
-ve parallax crosse
Projection: ZcL = 0

sed

/
/
/

J/1

Shot as (
iginal neg
actual

)tained
:orrection
ted)

lOt

50 '

Sh
r (

\
ot as o
>ptical
i^correc

Stereo
est

[wa

Ued)

40/y>

// aft*

40p
-2.2 mils

N -ve
Region

/
/ /
///
'/<*-*

//
/

22p
+6.4 m

) Stere<
s f test

'//

+0.8 mils
correctior

+ 10

+30

+25

+ 15

+5 0

-10

-15

Zc i.in mil
-20

)
-25

N factors at M = 218 (W = 15 ft; — *• No NI

Fig. 9. Graphical analysis of Slate 15 of The Block Swan, as Fig. 8, but showing

also how the Stereotest readings are plotted to give the depth

relationships on the camera negative.

270

October 1952 Journal of the SMPTE Vol.59

Data: M = 218, /. W = 15 ft, and

2.5 W = 450 in., .-. A = 1,125 sq in.
Z>! = 44p, /. 48P = AW
jc = 50 mm = 1.97 in., te =

1.25 in., /. C = 536.9 sq in.

From Eq. (14),

536.9 X 44

6,000
= 1.44 in.

-2.5

Hence, from Eqs. (11), (12) and (13),

2.10 X 2.34 =
2.00 X 1.53 =
4.9/3.1 = 1.6

4.9
3.1

From this it is safe to conclude, and
can indeed be observed in the film, that
some elongation of the side of the face
and the shoulders will be noticeable,
especially if the dancer turns so that the
same features undergo differing magni-
fication in quick succession. The more
interesting case in which the dancer pir-
ouettes with outstretched arms would
call for integration, since the depth occu-
pied by the arm stretching toward the
camera would be nonlinearly magnified
in a B-{- system. This difficulty can be
overcome by employing an extension of
the technique next to be described.

Interpreting the Stereotest

A graphical presentation, based on the
principle of Fig. 3, greatly simplifies the
study of scenes in space. So long as the
distance of a plane in the scene from the
camera is known, its position in space in
the theater can be read off in an instant,
together with the parallax which a point
in this plane has produced on the camera
negative, and finally the convergence and
interaxial separation which obtained
when the scene was shot. Figures 8 and
9 are the representation of Slates 35 and
1 5 respectively in The Black Swan. After
development, synchronized left- and
right-eye frames of the two Stereotests are
cut from the negative tracks and placed

under a special Swift traveling microscope
with pilot-pin registration. By placing
the two frames successively on the same
pins, the parallax between corresponding
points on the tests, at each distance, can
be read off with great accuracy. These
results from the actual film may be tabu-
lated as in Table IV.

Table IV

zc (mils)
40p 22p

Slate 35
Slate 15

-4.3

-2.2

+7.2
+6.4

It should be emphasized that, because
of the extremely small parallaxes needed
to produce a 5 N of only 0.1 (see Table
III), the most painstaking efforts must
be made to keep microscope reading
errors down to the lowest possible limits.
Figures 8 and 9 show how the 40 and 22
p points are plotted on a graph which
represents zc on the *-axis and distances
in p on the jv-axis. Since, on such a
graph, B — 0, B+ and B— systems are
equally represented by straight lines, it
is only necessary to lay a ruler between
the 40 p and the 22 p points. The result-
ing line represents all the stereoscopic
relationships in the negative, and the
*-axis can of course be additionally grad-
uated in N values for any assumed value
of M by using the relationship,

N=\-^ (-11)

In Figs. 8 and 9 this has been done for
M = 218, the magnification for which
the film was shot.

With the aid of a special protractor
(not shown in the diagrams), it is possible
to read off with great accuracy the actual
values of tc and <p (or h) which obtained
when shooting. These results may be
tabulated as in Table V.

No practical technique is imaginable
for changing the magnitude of the C fac-
tor after shooting (assuming that M re-

Spottiswoode, Spottiswoode and Smith: 3-D Photography

271

Table V

cot <f> tc (in in.)

Wanted Actual Wanted Actual

Slate 35 160
Slate 15 220

145 2.5 2.72
234 1.25 1.42

mains fixed), and therefore the slight
error in tc will result in any given span of
distances in the scene occupying a some-
what greater span of nearness factors in
the cinema than the stereotechnician
intended. On the other hand, errors in
the B factor resulting from inaccurate
convergence can be perfectly corrected in
an optical printing stage. This is be-
cause convergence is essentially no more
than the sideways displacement of the
films relative to the images formed on
them by the lenses, a fact which is easy to
recognize in the case of h, but which
applies also to <p. The method of cor-
rection will be apparent from Figs. 8 and
9. We know from the entries in the
stereocontinuity log the p distances which
were supposed to correspond with D0
and D1 (i.e. .V0 and A^ in the theater); in
Slate 35, D0 = 10p, and Dl = 30p; in
Slate 15, DQ = 13p and DI = 44 p.
These pairs of points enable us to plot the
"Wanted" curves for these shots. Figure
8 shows that the NQ (Do) line cuts the
"Wanted" curve at 10p, but the "Actual"
curve at 15p, thus indicating that an in-
creasing amount of divergence will be
introduced at M = 218 for scene dis-
tances greater than 15 p. Figure 8 also
shows that by displacing the "Actual"
curve sideways and in the increasing
negative direction through 3.5 mils (as
measured on the x-axis), N0 will be re-
established at 10p, thus producing the
"Corrected" curve. This is equivalent
to giving the image a lateral displacement
in relation to the perforations of —3.5
mils, and this figure is accordingly en-
tered in the correction table for the film.
The reason why the "Corrected" curve
still differs from the "Wanted" curve is,
as explained above, that tc is slightly

greater than it should be. This decreases
the gradient of the curve, and thus am-
plifies the change in N values for any given
range of object distances.

A correction of 3.5 mils corresponds to
a change of nearness factor (8N) of 0.3 at
M = 218. Corrections with this par-
ticular camera tend, however, to run
much higher, averaging about 10 mils
and sometimes exceeding 25 mils (dN =
2.2 at M = 218). This would mean
that an object at infinity would be repre-
sented stereoscopically as halfway from
the screen to the spectator, or vice versa
— an error which would, of course, com-
pletely destroy the 3-D effect of the scene.
With screens of larger size than 1 5 ft, the
error would be even greater.

The result of the correction to Slate 35
is that DQ is now correctly placed at N&
when projected with M = 218. Had
there been no error in tc, all other points
in the scene would also have been cor-
rectly placed. As it is, the banners at
the end of the shot project in the theater
at AYi instead of at A^.vs as planned.

The analysis of Slate 1 5 (Fig. 9) is car-
ried out in exactly the same way, and
here the correction is found to be +0.8
mils, the smallest ever encountered, the
plane of DQ having been moved back
merely from 13p to 11. 5 p.

When better camera equipment is
available, correction of every shot in this
way will not of course be necessary. The
technique of the stereotest will, however,
continue to be useful as a laboratory
check on the accuracy of the very precise
camera adjustments required — much
as the routine ZMog E curve provides a
daily or hourly check on film processing.
But this by no means exhausts the possi-
bilities of graphical analysis and optical
stereo correction. For instance, when
the layout of a set design is available, it
becomes possible to study the mechanics
of a complicated 3-D shot long before the
film reaches the studio. Planes in space
can be accurately charted, the necessary
camera constants determined, and if the
shot proves impossible, alterations can

272

October 1952 Journal of the SMPTE Vol. 59

be made in the set before rather than
after construction takes place. Again,
when the public learns how to look at
quick-cutting sequences in 3-D, it will
often be possible to build these up out of
material shot with an ordinary "flat"
camera, giving each shot a single plane

space by means of optical printing, and
ring this plane if necessary by means

optical zooms. The construction of

:h a sequence is greatly simplified if it
can be plotted in space, with the optical
corrections read off from the graphs.
The same technique may be applied dur-
ing the editing stage of an ordinary 3-D
film to readjust a shot which does not
fit into the space continuity finally de-
cided on. And lastly, optical printing
may be used to match infinity points (or
any other points) in converting films to
use on very large or very small screens.

Since optical printing is necessary with
our camera to provide left- to-right image
reversal, the transfer from original nega-
tive to master positive is made use of also
for the stereo correction and for the intro-
duction of the necessary optical effects.
Duping and printing then become nor-
mal contact processes. There are of
course limits to the width of the stereo
correction which can be printed on a
single film without trespassing too close to
the final projector aperture. If the cor-
rection is too large, it must be split be-
tween the two bands of film. However,
the larger the screen for which the film is
shot, the smaller the absolute magnitude
of the corrections. Furthermore, an ad-
ditional width is provided for the cor-
rections on each film by the printed-on
stereo window.

The Stereo Window

This is the last printing stage to which
the film must be submitted. The Black
Swan has a fixed stereo window at ap-
proximately N2 (with M = 218), con-
taining patented fusible components
along its top and bottom edges, so that
these contribute to the stereoscopic effect
nearly as much as do the vertical sides.

The window also could be incorporated
at the master positive stage, but ex-
tremely high contrast is necessary in a
traveling matte to avoid fogging the
image, and it is therefore best printed on
at the release print stage.

The stereo window is an essential com-
ponent of most 3-D films, and its exist-
ence and position in space must be con-
templated from the beginning. More
than half of the shots in The Black Swan
were designed to occupy the full stereo-
scopic space between NQ and N% (i.e.
A#z) ; but as the scene was a ballet stage
with dancers on it, effective space would
have been seriously telescoped had not a
forward window permitted a free move-
ment of the image out to a distance half-
way between the screen and the spec-
tator.

Appearance of the Scene in the Theater

It is now time to stand back from the
technicalities of production and ask how
the two shots we have so often referred to
appear to the ordinary audience in
the movie theater. In the first place,
whether they are conscious of it or not,
spectators will see the entire scene framed
behind the forward window, with the
exception of one or two self-supporting
objects such as the banners in Slate 35
and Beryl Grey's arms and back-bent
body in several shots. Since the screen,
if free from blemishes, becomes invisible
in a 3-D film, the window is easily mis-
taken for it. Thus an audience might be
led to comment on The Black Swan,
"Practically nothing comes out in front
of the screen," although, in point of fact,
almost half the film does so. But the
actual — even if unrecognized — use of
theater space has one extremely impor-
tant advantage which we have often
heard commented on during commercial
presentations of the films. Because of
the increase of stereoscopic depth mag-
nification (md) with distance from the
screen, the spectator in the most distant
balcony seat has a view of the film which
is just as dramatically effective as that ob-

Spottiswoode, Spottiswoode and Smith: 3-D Photography

273

tained by a person sitting comparatively
close to the screen.

In a stereocinema, distortions are
usually least at a seating distance of
2 to 2.5 W, and if — but only if — the pic-
ture has been shot so as to be acceptable
from this position, it will not as a rule
appear unnaturally elongated even if
viewed from much farther away. This
is due to the inverse effects of mb and mw
described under the heading "Binocular
Magnification," earlier in this paper.
Practical viewing experience reveals a
substantial constancy in the depth-
appearance of the image between the
front and back seats of any normal thea-
ter; but this will only be true if N values
of 2 or more are employed continuously,
for otherwise the distant spectator will be-
come conscious of the gap existing be-
tween himself and the screen. In our
experience, provided that a sufficiently
high level of technical perfection is
achieved in the production and projec-
tion of a 3-D film, nearness values as high
as Ns can be held continuously (for ex-
ample, in a stereo window), with much
larger values for the normal duration of
an especially dramatic scene.

Granted, then, that the scene in The
Black Swfln will be framed in an N2 win-
dow; and that the audience, though for
the most part unconscious of this fact,
will be aware of seeing a picture totally
different from the normal one, and differ-
ent too from a stereo film presented
wholly behind the plane of the screen.
Granted this, what else will the audience
be aware of? In the first place, the fact
that their eyes can now scan the scene in
depth means that the visual content of
each shot will be much increased, and
this in turn necessitates holding the shot
longer on the screen. Today, when few

audiences have seen 3-D films before,,
quick cutting is ineffective, since each
shot takes an appreciable time to estab-
lish itself, after which its quick disappear-
ance produces an effect of disappoint-
ment and even annoyance. This is an
extension of the principle on which color
films tend to be cut somewhat slower
than black-and-white ones. Secondly,
the audience will be much more aware of
the importance of depth relationships in
a scene. Figure 10 shows a shot in The
Black Swan which is of a type particularly
impressive in 3-D. Whereas in a flat
film it would achieve no more than the
normal effects of deep focus, the third
dimension gives the foreground figure an
almost physical effect of size and mass-
iveness. Even when the spectator is con-
sciously watching the White Swan trying
to make her presence noticed, he feels
his eyes drawn to the menacing figure
of the Enchanter standing much closer
in the foreground and trying to banish
her away.

In the third place, the audience almost
completely loses the impression that it is
watching the photographic rendering of a
scene. Actual reality seems to lie before
it, and when the film is in color this
reality is almost complete.

Thus in the first scene we have been
considering, the Male Variation danced
by John Field will appear almost as if
one were present in the theater. The
raising of the banners right in front of
the eyes produces by contrast a momen-
tary feeling of complete surprise; and
after a brief pause, the successive lifting
of four pairs of banners out of scene —
flowing in the same unbroken rhythm
— disguises the fact that the scene has
changed and thus introduces an element
of fantasy when both a new decor and a
different dancer are revealed.

Part III: A Critique of Existing Procedures

It may well be asked how, in the
absence of a general transmission theory,
proper camera and projection conditions

could have been set up for the stereo-
scopic films produced up to now and
those in current production by other

274

October 1952 Journal of the SMPTE Vol. 59

groups. The answer is threefold. First,
the basis of an accurate theory was laid
just prior to the war by Professor J. T.
Rule,8 and was apparently used by J. A.
Norling in the production of his well-
known and very successful films. Sec-
ond, a number of pictures have been
produced outside the United States on
the basis of no proper transmission theory

Fig. 10. The third dimension in this type of shot gives the foreground
figure an almost physical effect of size and massiveness.

at all, severe eyestrain having been
avoided only because the size of the
projection screen was very small. Third,
and most recently, the early work of
Rule has been overlooked or ignored,
and a number of simplified procedures
have been suggested, many of them the
subject of exaggerated claims, such as
that they completely eliminate dis-
tortion, or that they make 3-D filming

Spottiswoode, Spottiswoode and Smith: 3-D Photography

275

conform to the procedures of the flat
film, yet without loss of effect.

In this Part we shall discuss in some
detail, using the method of analysis
already derived from the general theory,
two typical proposals, both in current
use and both claimed to provide a
perfect solution to all problems of
stereoscopic transmission. The first
makes use of a fixed interaxial separation
of the camera lenses, and a variable con-
vergence; in the second the convergence
is fixed, but the interaxial separation is
made variable.

Viewing of Real Objects
and Stereo Images

It has been suggested — notably by
Dewhurst9 in Great Britain and more
recently by an influential group in the
U.S. — that the problem of 3-D filming
is very simple: all that is necessary is
to provide a fixed lens separation (tc)
approximating that of the human eyes
and then converge the optical systems
on some appropriate plane in the
scene — this plane appearing, of course,
in the plane of the screen when the film
is projected with ZCL = 0. It has been
further suggested that the convergence
control ought to be coupled to the lens-
focusing mechanism in such a way that
DI is always the distance to the plane of
sharpest focus. Thus, following focus
would automatically alter the con-
vergence, and (since tc is already fixed)
no special stereoscopic adjustments of
any kind would require to be made.
This, it is held, would reproduce the
conditions of natural vision, and would
provide strain-free viewing of the image
by all spectators.*

* The same idea has recently occurred to
the first producer of 3-D motion pictures
in Hungary, M. Felix Bodrossy. "The
Hungarian method," he writes, "solves the
problem simply and radically: it starts off
from the way the eyes work, and imitates
nature. The eyes always focus auto-
matically and at the same time converge
on the object they look at. Our cameras
do the same thing."10

The parallel with the human eyes is
simple and attractive; but, from what
has been said above, it will be apparent
that the viewing of a stereoscopic image
cannot at present be made to resemble
human vision at all closely. The image
in space is not even an optical image;
it is a mental construction from data
supplied solely by overlapped images on a
flat screen. This construction is accom-
plished by methods not used in normal
vision; for example, the spectator's eyes
must remain focused at the screen dis-
tance, but they will be varyingly con-
verged according to the distance of the
point of attention, which may be much
nearer or much more remote. Further-
more, in the real world, sense-data re-
main more or less constant when spec-
tator and scene are fixed; but stereo-
scopic data may be made to vary widely
according to projection conditions, and
indeed cannot be kept constant when the
size of the screen is changed. It is
therefore not to be expected that a mere
reproduction at the camera of the human
eye separation — in the absence of
human viewing methods — will of itself
produce strain-free viewing. This can-
not be so simply achieved until it becomes
possible to create real or virtual 3-D
images in space.

Limitations of Fixed-fc Systems

Meanwhile, stereo camera systems
which make use of a fixed "human" lens
separation of 2.5 in. must be treated as
having an awkward limitation common
to all fixed lens systems designed to film
pictures for large screens. The trans-
mission system obtaining with a fixed
value of tc can be very clearly exhibited
on a graph similar to Figs. 8 and 9.
Reference to the section "Depth Range
in the Scene," earlier in this paper, will
show that the slope of the transmission
lines is a function of the C factor (i.e.
Mfctc) and t; and therefore, if M is as-
sumed fixed for the film, tc is fixed on
principle, and fc represents the focal
length of the lens in use, all possible trans-

276

October 1952 Journal of the SMPTE Vol. 59

Object distances
from camera
60 (in rhos)

— ->XB+ REGION -

_ -^ — _ ^ _ -

7717
Region of / \S_
divergence I

B- REGION

\l \

N factors at M= 218 No

Ni(ZCL=0)

Fig. 11. Graphical analysis of "human vision" technique (i.e., tc fixed at 2.5 in.).

For M = 21 8, fe = 50mm, all depth range possibilities are comprised in a series of parallel
lines, such as those shown at 10p intervals, in the horizontally shaded region bounded by
B = 0. For p values > 60 (distances < 8 ft 4 in.), extend the graph upward; forN> 3,
extend it to the right. For/c > 50mm, the parallel lines slope proportionately less steeply,
and the depth range decreases ; for fe < 50mm, these lines slope more steeply, and the
depth range increases. For M > 218, the region of divergence extends to the right,
the intervals N0, NI, N2 . . . becoming proportionately smaller, NI remaining at zc = 0.

mission lines on the graph will have the
same slope, and must therefore run
parallel to one another.*

Figure 1 1 displays all the possibilities
of such a transmission system, assuming
tc = 2.5 in., and taking M = 218 and
fe = 50 mm (i.e. 1.97 in.), so as to enable
a direct comparison to be made with the
shooting of Slate 15 of The Black Swan.

Then, from Eq. (8b),

* When the focus and convergence are
coupled, this statement is not strictly true,
for fe is properly the lens-to-film distance,
which increases slightly as the lens is focused
nearer. Hence, as DI is brought nearer to
the camera, the C factor will increase
slightly and the depth range will be corre-
spondingly reduced. This is a second-
order error, which is ignored in Fig. 11.

D1 -

2.5 X 6,000
218 X 1.97 X 2.5

rhos
13.97 rhos.

This enables us to draw the B = 0 line
in Fig. 11, which also shows representa-
tive transmission lines drawn in at arbi-
trary intervals of lOp. The area under
the B = Q line represents the B — type of
transmission, which gives rise to card-
boarding and is therefore almost always
undesirable; hence the camera conver-
gence must never be set to give DI less
than 13.97p (i.e. di more than 35 ft 9 in.).
When the lenses are focused at infinity,
they must not, as might be expected, be
aligned with their axes parallel; alter-
natively, if the lens and convergence
mechanisms are coupled, the lenses must

Spottiswoode, Spottiswoode and Smith: 3-D Photography

277

278

October 1952 Journal of the SMPTE Vol. 59

not be focused beyond 35 ft 9 in. for M =
218. However, the minimum conver-
gence will alter with the size of screen for
which the picture is shot, and the focal
length of the lenses in use, which might
give rise to awkward mechanical com-
plications.

Much more serious than this, however,
is the restriction on the depth range im-
posed by such a method of shooting, and
— in the coupled arrangement — the
undesirable and highly artificial pushing
of things nearer and farther away in
space, which will tend to negative the
3-D effect of the film, especially when
complicated studio shots are undertaken.
This can best be demonstrated by revert-
ing to Slate 15 of The Black Swan, and
showing how it would have appeared in
space if shot by the "human vision"
technique.

Figure 12 is a repeat of Fig. 11, save
that it is extended to cover a higher range
of nearness factors, and is marked with
the actual distances found in Slate 15.
Curve 1 shows the result of setting the
back of the scene (13p) at infinity, i.e. at
DO, the method employed in the actual
shooting. But now the front set of ban-
ners (at 79p) will come out to -/V4 7, i.e.
(79 - 13)/13.97, which is almost J of
the distance from the screen to any spec-
tator. This is much closer t'lan the cut-
ting continuity allows, and, in the
opinion of many, enters the region of eye-
strain. Certainly, the extreme nearness
of the banners would be quite out of keep-
ing with the rest of the film. No other
fixed setting is possible, since it would
produce divergence on the back of the
set, even with the extremely modest as-
sumed magnification of 218 (i.e. a 15-ft
image in the theater).

Thus a variable convergence for this
shot is required by the "human vision"
system under discussion, and we may
conveniently assume that the converg-
ence is coupled to the lens focus system
in the way already described. The shot
opens with the banners at 79p (6 ft 4 in.),
and since at this distance, using a 50-mm

lens at an aperture of //2.8, the depth of
focus is only about 17 in., it would be
necessary to focus with some precision for
the distance of the banners themselves.
This would cause them to appear in the
theater at NI (see Curve 2), and once
again the wanted effect would not be
achieved, though this time the banners
would be too far away, instead of too
near. As the first pair was lifted, the
plane of focus would move gradually far-
ther away, passing through positions such
as Curve 3. Following accepted tech-
nique, the camera operator would follow
focus in such a way that each pair of ban-
ners in turn would occupy the plane of
sharpest focus; but this would have a
disastrous stereoscopic effect, in that it
would bring all the banners into the same
image plane (i.e. on the screen), and thus
would wipe out the wanted recession in
space.

When the last banners had been raised,
the focus would rest at 27p, and the back
of the set would be correctly placed at
13p. But towards the end of the shot,
Beryl Grey dances forward to 48p from
camera, where she would be out of focus.
It is therefore necessary to alter focus
again, and according to normal practice,
the dancer would be held in the plane of
sharpest focus, shown as Curve 4 in Fig.
12. This would not only completely
neutralize her forward movement in
space, but would create divergence on
the background, which would still be
sufficiently in focus to be fusible. The
only way out of the dilemma of neutraliz-
ing depth is to juggle with the depth of
focus, placing very near objects at the
limit of the zone of acceptable sharpness
in order to correct as well as possible
their misplacement in space. This pro-
cedure would unquestionably be much
more inconvenient than having indepen-
dently adjustable stereo settings for it
would contradict accepted camera prac-
tice and would give rise to a method of
shooting in which the sharpness of focus
was always under suspicion.

The problem of divergence is even

Spottiswoode, Spottiswoode and Smith: 3-D Photography

279

more intractable. Figure 12 shows that
points at 13p will be separated by 6.26 in.
on the screen instead of the proper 2.5 in.,
which would induce serious eyestrain,
especially for spectators in the front rows
of seats. If the magnification is raised
from 218 to 300 (i.e. a screen width of 20
ft 8 in.), the separation on background
points would amount to 8.6 in., more
than three times the separation of the
human eyes. It should be remembered
that divergence does not occur at all in
natural vision; its physiological effect
can be extremely uncomfortable.

Distortions With Fixed-fc Systems

But this is not the last of the disadvan-
tages of a "human vision" camera ar-
rangement. The use of large B factors
entailed by employing a value of tc which
is often too big for the size of screen and
the depth range to be compassed, leads
to serious distortion of the shape of ob-
jects, as may be seen by a comparison of
the example worked out under "Image
Distortion in the Theater," earlier in this
paper, with the same scene shot accord-
ing to the precepts of "human vision."
The data will be exactly the same, save
that tc = 2.5 in. instead of 1.25 in., and
that the dancer (who will be in the plane
of sharpest focus) will be moved very
slightly back from N\ .09 to N\. When
these new values have been substituted,
along with the unchanged data, in Eqs.
(11) to (13), the results in Table VI are
obtained, which for convenience are
placed alongside the characteristics of
the shot in the film.

Table VI. The Black Swan, Slate 15,

Stereo Distortions at the Plane of the

Dancer's Final Position. M = 218;

V = 2.5PF.

By "human
vision"

In the
film

md 12.4
niu) 3.4

4.9
3.1

M 3.6

1.6

What has happened with "human
vision" is that the width magnification
has been kept down by making tc equal
to t, which is one of the conditions for en-
suring that mw — 1 (see Eq. (15)). On
the other hand, the depth magnification
has increased enormously owing to the
squared term in Eq. (11), and this has
more than doubled the distortion of
shape, as indicated by the figures for the
shape ratio.

This consequence of a "human vision"
approach can be even more clearly dem-
onstrated by the graphical technique
already described. Figure 13 is in
essence an enlargement of the relevant
part of Fig. 12. It shows Beryl Grey's
shoulder placed at 48p (10 ft 5 in.) from
the camera, with arm outstretched as she
pirouettes, so that the fingers are at 60p
(8 ft 4 in.). The x-axis has been gradu-
ated in N values, so that the value of P
(distance from spectator to a point in the
image) can be readily calculated from
Eq. (1). By taking two points, one at
the shoulder and one at the fingertips,
the actual stereoscopic length of the arm
can be found by simple subtraction, in
spite of the fact that the magnification
varies nonlinearly between the two
points. Figure 13 shows that the arm
length, as shot for The Black Swan, is 102
in., whereas by "human vision" prin-
ciples it would have been 208 in., or more
than twice as great. The overall depth
magnification works out as 4.1 in the first
case, and 8.3 in the second, since the real
arm length is 25 in.* As the dancer
continues her pirouette, her outstretched
arm moves into a plane parallel with that
of the camera lenses, where its magnifica-
tion will be uniform, and is given by mw
in Table VI. The two shape ratios are
therefore 1.2 for the film and 2.4 for
"human vision," which is again twice as
much distorted.

* The overall magnification is of course
lower than the magnification at the
shoulder, because md decreases as N in-
creases, and is therefore least at the finger-
tips.

280

October 1952 Journal of the SMPTE Vol. 59

Distance from
camera, (rhos)

Plane of dancer's
fingertips

Curve (A)

Curve (B)

- - Plane of dancer's
shoulder

N! 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 N2

Fig. 13. Enlarged section of Fig. 12, with "human vision" rendering of
Slate 15 (Curve B) compared with shot in film (Curve A). N values may be
converted to image distances from spectator (P) by Eq. (1) (P = V/N}. Assume
spectator seated at 2.5W, i.e., 450 in. from 15 ft screen. Let P = image distance
to dancer's shoulder, P' to her fingertips, when her arm is outstretched to the
spectator. Hence, stereoscopic length of dancer's arm = P — P'.

From Curve B, "human vision," P = 450/1, P' = 450/1.86, .-. P - P' = 208 in.
From Curve A, shot in film, P = 450/1.13, P' = 450/1.52, .-. P - P' = 102 in.

The general applicability of a "human
vision'.' technique can perhaps be most
quickly judged by a statistical summary
of the te values employed in some recent
pictures. The settings indicated by cal-
culators such as the Stereomeasure and
the Polaroid Interocular Calculator
naturally give no preference to the value
of 2.5 in., which is merely one setting in a
wide and infinitely divisible range; but
if, to give "human vision" all permissible
latitude, we assign it the whole span of
tc values between 2.3 in. and 2.7 in., we
can analyze its limitations in the light of
actual tc figures from productions. Pic-
ture A is a studio film shot in sets of
normal dimensions ; Picture B is a docu-
mentary film shot principally out of
doors.

Table VII. Number of Shots Lying
Inside and Outside the "Human Vision"
Range for Two Typical Productions

Less More

than 2.3- than
2. 3 in. 2.7 in. 2.7 in.

Total

Picture A
Picture B

16
6

20
10

1
29

37
46

Thus 46% of the shots in Picture A,
and 76% of those in Picture B, fall out-
side the "human vision" range when cal-
culated according to the general theory,
and without any preconception that t
must always equal tc. It must be re-
membered that the scene we have been
discussing in such detail is not in any way
abnormal, but is representative of in-

Spottiswoode, Spottiswoode and Smith: 3-D Photography

281

numerable shots which try to exploit in-
telligently the possibilities of a properly
conceived 3-D system. Almost any
method of stereoscopic shooting will
handle mid-shots and long-shots (in
which the depth range in reciprocal units
is not great) quite satisfactorily, and will
handle all shots provided that they are
projected on small screens of 8-ft or 10-ft
width.

Limitations of Fixed-^ Systems

The scheme for equating tc with t is by
no means the only system put forward
with the idea of simplifying and improv-
ing 3-D film making. Another typical
arrangement is that of "Verivision,"
which has gained some currency in
Holland, the home of its inventor, Dr.
F. H. Reijnders,11 who hopes to secure
completely distortion-free reproduction
by fixing the camera convergence angle
permanently at <p = 0.3°.* At the same
time tc is made variable, and set at such
a figure that the fixedly converged lens
axes always intersect in the nearest plane
of the scene.

It can readily be shown that "Veri-
vision" (which disregards the effect of
screen size) reduces to the simple rela-
tionship DQ = 0.44Z>i. This is graphed
for distance .increments of 10 p in Fig. 14,
which clearly shows the possibilities and
limitations of the system, f It has the

* No explanation has been given for the
choice of this particular angle, and Dr.
Reijnders himself has prudently — though
perhaps optimistically — claimed a patent
on all values of <p between 0.15 and 0.6°.
f For purposes of comparison, the j-axis
has been graduated with the values of tc in
mm obtained from Dr. Reijnders' formula
for different values of D\.

advantage over "human vision" that,
when the foreground plane is very close,
tc becomes very small and the depth
range is correspondingly increased, as
may be seen by the increasing gradient
of the curves corresponding to the larger
p values. On the other hand, whereas
some scenes can be reproduced by
"human vision" with freedom from
distortion (i.e., when Eq. (15) can be
satisfied), "Verivision" cannot possibly
eliminate distortion except under one
special and unlikely condition. Ref-
erence to Fig. 14 will show that all the
characteristic curves intersect at a
single point in the x-axis. To meet
the first orthostereoscopic condition,
B = 0, it is necessary that this point
should correspond with N0) and this,
as the figure shows, occurs when ze =
+20.5 mils, which from Eq. (3) gives
M = 122, corresponding to a screen
width of 8 ft 4 in., a size not particularly
well adapted to commercial produc-
tion.

A further limitation of "Verivision"
is that it imposes a method of filming
which eliminates all N values greater
than unity.

To sum up, it is incorrect to suppose
that the functions of convergence and
interaxial separation are interch^nge-
able, and that either can be fixed at an
arbitrary value without impairing the
flexibility of the system. The B factor
and the C factor are entirely distinct.
Moreover, since the C factor cannot be
altered after shooting (given the size
of the screen), errors in te caused by
incorrect filming methods cannot after-
wards be amended.

Shooting a 3-D film demands two
major changes in production methods:
a change of attitude on the part of the
director, and a change of camera
technique.

Part IV: Conclusions

The director of a 3-D film has an obli-

gation to explore space relationships in
his sets and between his characters which
he would pass over in a normal flat film.
If he neglects to do this, and merely em-

282

October 1952 Journal of the SMPTE Vol. 59

tc(mm )
26.1

D^rhos)
60

50 N values
> 1 not
permitted

Region of
divergence

(M=218)

15 No 10
•< Zc (in mils) *•

Fig. 14. Graphical analysis of "Verivision" technique (<p fixed at
0.3°, tc adjusted so that optical axes intersect at A)- Converging
characteristics, shown at 10p intervals to 70p, show very limited depth
range possibilities of the system, since only unshaded central area can be
employed, and only that part of it bounded by available limiting values
of tc. Note that B = 0 only when point of intersection of characteristic
curves occurs at N0. This corresponds to zc — 20.5 mils, or M = 122.

phasizes the extra dimension by placing
some meaningless post or tree or lamp-
stand in the foreground of each shot, the
audience will become as weary of these
tricks as they became of the endless knives,
ladders and hurtling baseballs of the pre-
war anaglyphic pictures.

The left- or right-eye track of a 35-mm
double-band stereo film may without
modification be presented to a wider
audience in unconverted theaters as a
normal flat film. However, the more
successfully the film's director has

thought himself into the new world of the
3-D film, with its different space rela-
tions, rhythms of cutting, and use of opti-
cal effects, the less effective will be the
flat version by comparison with what the
same director would have made out of
the same story had he concentrated on it
alone.

The translation of the director's ideas
into 3-D film demands a comprehensive
knowledge of stereoscopic transmission
theory — in just the same way as an
electronic organ designer could not inter -

Spottiswoode, Spottiswoode and Smith: 3-D Photography

283

pret a musician's wishes without a proper
grounding in audio engineering. A
stereo transmission theory has now been
evolved, some elements of which we have
described ; and to it has been added the
beginnings of a new study of the psycho-
logical aspects of stereo viewing — corre-
sponding in our analogy to a study of the
modes of hearing. This theory is framed
in a carefully studied terminology, which
we hope may become the basis of an
agreed nomenclature, for much time has
often been wasted in new subjects by dis-
cussing names instead of things.

Once the transmission theory and the
terminology have been established, cal-
culators may be designed and stereo-
technicians trained, so that the produc-
tion of a 3-D film takes very little longer
than a flat film. Spatial effects can be
controlled with positive assurance, sets
can be designed to achieve effects un-
obtainable in the flat film, and back pro-
jection and traveling matte processes can
be developed with accurate knowledge of
what is needed and of the tolerances
which have to be met.

These things cannot be fully achieved,
however, if the design of the camera
has been cramped by artificial restric-
tions on the two main stereoscopic
variables. Pictures which are shot for
projection to small nontheatrical au-
diences are indeed much less critical than
pictures shot for the big screens in com-
mercial theaters. The former may per-
haps prove satisfactory if calculated
by rule-of-thumb methods; for the
latter much greater precision is needed
if professional standards are to be met
and audience discomfort and eyestrain
avoided.

Mathematical analysis is needed as
a tool of space control in the filming of
3-D pictures because the mental con-
struction of a space image from data
originally incorporated on two pieces
of flat film bears only a remote re-
semblance to the human process of
seeing objects "in the round" as they
exist in the external world. From this

analysis, as we have seen, flow important
consequences relating to the design of
3-D film cameras. These may be
summed up as follows.

When M is large, and /c, in the
interests of composition, is under the
cameraman's control, te must be ad-
justable over a wide range, and in
particular it must be capable of assum-
ing very small values (of the order of
1 in., or even less) to make possible
interesting camera effects of extreme
depth range both in the studio and out-
doors. Large values of te are essential
for getting a big depth content on small
screens, and for producing startling
space effects on large ones.

A fixed value of tc eliminates most of
these possibilities, and greatly exagger-
ates the distortion of objects to which a
stereo system is in any case prone. If
convergence and focus are coupled, other
undesirable effects make their appear-
ance : following focus helps to negate the
movement of the camera through space
by bringing everything in the foreground
into the plane of the screen ; at the same
time it becomes almost impossible to give
near objects an N value much greater than
unity, since they will automatically go out
of focus in the attempt. But large N
values — quite apart from their occa-
sional use as stunts — are essential to the
bringing of the picture close to every
spectator, which is one of the outstanding
advantages of the space film.

A fixed value of <p has equally little
logic to support it, and it takes the con-
trol over the position of the image in
space out of the hands of the cameraman
and director to whom it belongs, and
fixes it in accordance with some partial
or erroneous theory.

By contrast, the general theory out-
lined in this paper — unlike the patented
procedures discussed in Part III — does
not prescribe any fixed camera technique
or impose the use of any mechanical
device. The director and cameraman
should be able to make a free choice of
the space effects they require the ulti-

284

October 1952 Journal of the SMPTE Vol. 59

mate audience to experience; the stereo-
technician will then be able to tell them
how that effect can be produced, pro-
vided that the camera equipment is
sufficiently flexible and that psycho-
logical viewing factors are properly
taken into account. A true parallel,
therefore, would be with the science of
sensitometry, which does not attempt to
prescribe fixed exposure settings, but
does in fact analyze the consequences of
making toe and shoulder exposures,
altering the developing time, using
different types of emulsion, and so on.

In the same way, a valid transmission
theory will enable the stereotechnician
to determine what will be the geometrical
form and position of the space image
under all possible camera, optical
printing, projection and viewing condi-
tions. The effects of altering the space
structure of the image in passing from
shot to shot, as well as the space dis-
tortion in individual shots, which are
revealed by this analysis, will be evalu-
ated in the light of previous experience
in seeing 3-D films. Not only will the
members of the production team them-
selves become increasingly sensitive to
the appearance of a new kind of film
image, they will come to know what is
and what is not effective in terms of
audience response.

Already a substantial body of pro-
duction experience has been built up
in the last two years in the course of
developing and applying the principles
outlined in this paper. A dozen films
have been produced which have been
commercially exhibited in half as many
countries and seen by audiences now
nearing the 3 million mark.

If the full possibilities of the 3-D
medium are to be exploited, the design
of new cameras should be put in hand
forthwith. Both theoretical analysis and
experience point to the need of a wide
flexibility in the tc and h variables, and
of a precision of adjustment and film
registration equal to that which must
be attained in 3-strip color cameras.

By using separate 35mm films for the
left- and right-eye images, and by
interposing the minimum number of
additional glass surfaces between scene
and film, these requirements can be
achieved, though there is at present
only one camera in the world (the work
of J. A. Norling) of adequate precision
and flexibility.

Granted adequate cameras, there is
no reason why films as ambitious as
any now made in Hollywood should not
be undertaken in the vastly more
powerful 3-D medium. The knowl-
edge thus acquired of production
problems and audience response would
remain of undiminished value were
polarized projection to be replaced in
the future by some type of integral or
"free-vision" viewing screen; for though
the means of separating the images may
change, their appearance in space is
likely to remain unaltered. For example,
the parallax barriers recently classified
by Kaplan in a paper of fundamental
importance,12 one and all give rise to an
image geometry identical with that al-
ready analyzed in Part I for a piano-
stereoscopic system.

As long as audiences will, therefore,
accept for the time being the slight in-
convenience of glasses — which recent
European experience seems to bear out —
there is no reason why major studios in
the U.S. and Britain should further delay
the production of at least a few dramatic
films to determine whether or not they
are the answer to a declining box office.

At the same time, other developments
in the projection field will be under
way, which will still further close the
gap between the spectator and the
scene, and will reinforce that sense of
participation in the drama of a film
which alone, perhaps, can prevent the
great audiences in the motion picture
theaters from dissolving away into little
audiences in front of home television
screens.

Spottiswoode, Spottiswoode and Smith: 3-D Photography

285

Acknowledgments

For the material of Part II, the
authors wish to express their gratitude
to the staff of Anglo-Scottish Pictures,
coproducers with Stereo Techniques,
Ltd. of The Black Swan, and especially
to Leonard Reeve, the director, Bernard
Davies, who bore patiently with the
camera, and Alvin Bailey, the editor.
Our thanks are also due to Brian
Anthony, head of the Optical Depart-
ment, Denham Laboratories, who car-
ried out the stereo corrections on The
Black Swan and a number of other
pictures.

References

1. J. A. Norling, "Three-dimensional
motion pictures," Jour. SMPE, 33:
612-634, Dec. 1939; "Progress in
three-dimensional pictures," Jour.
SMPE, 37: 516-524, Nov. 1941. Also
"The stereoscopic art, Parts 1-4,"
PSA Jour., 17: 703-708, Nov. 1951;
17: 738-742, Dec. 1951; 18: 19-25,
Jan. 1952; and 18: 122-125, Feb.
1952.

2. Norman McLaren, "Stereographic ani-
mation," Jour. SMPTE, 57: 513-520,
Dec. 1951.

3. Raymond Spottiswoode, "Progress in
three-dimensional films at the Festival

of Britain," Jour. SMPTE, 58: 291-
303, Apr. 1952.

4. Raymond Spottiswoode and Nigel
Spottiswpode, The Theory of Stereo-
scopic Transmission, University of Cali-
fornia Press, Berkeley, Calif., 1953.

5. John T. Rule, "The geometry of
stereoscopic projection," J. Opt. Soc.
Am. 31: 325-334, Apr. 1941.

6. Sir David Brewster, F.R.S., The
Stereoscope, John Murray, London,
1856. Also see Edin. Trans., 15: 663,
1846.

7. Report on Screen Brightness Com-
mittee Theater Survey, Jour. SMPTE,
57: 238-246, Sept. 1951.

8. L. Dudley, "Stereoscopy in the Tele-
cinema and in the future," British
Kinematography, 18: 172-181, June
1951.

9. H. Dewhurst, "Auto-precision stereos-
copy," Phot. J., Sec. B, 92B: 2-24,
Jan.-Feb. 1952.

10. Felix Bodrossy, Magyar Technika, May
1952.

11. French Patent No. 938,023. M. Bon-
net, "Etude du Procede de Relief
'Verivision Holding,' " Bulletin de
I* Association Fran^aise des Ingenieurs et
Techniciens du Cinema, 9: 11-16, 1951.

12. Sam H. Kaplan, "Theory of parallax
barriers," Jour. SMPTE, 59: 11-21,
July, 1952.

286

October 1952 Journal of the SMPTE Vol. 59

Drawing in Three Dimensions for
Animation and Stereoscopic Processes

By ERNEST F. RISER

Stereoscopic mathematics are far too complicated to apply easily and speedily
to every point in the many drawings and cells required to obtain motion in
animated films, or in a usable volume of art for commercial or lecture pur-
poses. The following procedure was developed to allow stereo drawings to
be made with a minimum of time and effort and still produce practical three-
dimensional material.

AN THIS METHOD the artist draws to scale
directly from the subject as in conven-
tional art practices but also adds the
scale distance he may be from the object,
as well as the depth of subject measure-
ments, to obtain stereoscopic effects.
He is able to compute the amount of
stereo depth necessary in any part of the
drawing; and he is able to determine the
size of the image which will appear on
the screen. Stereo rules and principles
as outlined in this paper do not neces-
sarily apply to true stereoscopic me-
chanics, as these practices were developed
only while making this simplified pro-
cedure workable. Single objects for ad-
vertising and lecture purposes drawn in
stereo differ from scenic stereo art in that
they are usually small in size and show
considerable detail without much height,
width or depth. This necessitates spe-

A contribution submitted June 25, 1952,
by Ernest F. Hiser, Dept. of Medical Illus-
tration, School of Medicine and University
Hospitals, The University of Oklahoma,
Oklahoma City 4, Okla.

cial consideration when preparing them
for three-dimensional viewing.

Figure 1 (a) shows the left (L) and right
(R) eyes from above, looking to infinity
with parallel lines of sight. While it is
optically possible to widen these twin
lines to some extent, natural visual ad-
justments do not depend on this ability.
Stereoscopic vision is practically non-
existent beyond 1000 to 1500 ft, but from
200 ft to within a few inches of an ob-
server the portrayal of a third dimension
becomes a very noticeable accomplish-
ment. The parallel sight lines indicated
are the width of the eyes, a maximum of
2f in., and for all practical drawing pur-
poses that figure is used.

Any object within the range of stereo
vision will cause the eyes to converge or
"toe in" just enough to focus on that
object and its particular point of interest.
While this point of interest is actually a
point, a vertical flat plane at that point is
important in this method of making
stereoscopic drawings. This flat plane
is to be considered as the "window-
plane," and is located exactly where the

October 1952 Journal of the SMPTE Vol. 59

287

viewing screen will be upon projection,
or where the aerial image appears upon
viewing by other methods. The point
of focus or interest for any object can be
at any depth level within the boundaries
of that object. The term "window-
plane" derives from the fact that in a
stereo picture all objects appear to stand
out or recede from the black edge of the
picture as if they were being viewed
through a picture frame, or window.

Although the point of focus may be
placed on any part of the subject for
emphasis, a dead-center location will give
the maximum overall stereoscopic effect
for the subject. When the picture area
includes several objects, a dead-center
point of focus will provide excellent
depth separation. All objects drawn to
the front of the window-plane will appear
nearer to the observer, while all objects

drawn to the rear will appear farther
away. This plane interposed into a
stereo scene with the eyes set at infinity
will cause the sight lines from L and R
to pass through it as L1 and R1 (2f in.
apart), and the two flat drawings which
constitute one stereo drawing will have
their identical components separated by
that scale distance on the window-plane.

In Fig. 1 (b), the lines of sight are toed in
until the point of vision is focused upon
the window-plane. All points on one
drawing which are to appear on this
plane will coincide exactly with the same
points on the other drawing.

In Fig. l(c), the point of focus is brought
forward to A, where the toe-in or crossing
of the eyes causes the lines of sight to pro-
ject upon the window-plane as R1 and
L1, and in reverse order to that of in-
finity. As there is a limit to the toe-in
effect (with the danger of obtaining ghost
images), this amount should again be not
more than 2f scale in. on the window-
plane. The point where the sight lines
cross, A, will always be exactly one-half
the distance of the window-plane to the
observer. Since the coincidal points of
focus are separated by toe-in as in (b), the
object focused upon will appear nearer to
the observer.

In order that these measurements be
made practical, it is essential that the
screen size is visualized. A 40-in., 6-ft or
18-ft screen with a well placed and
planned image size must be kept in mind
throughout the process so that parallax
on the window-plane can be computed
easily for its comparative to scale likeness
on both drawings.

The first drawing to be made can be
designed without too much regard for
stereo principles. It should have correct
perspective, and the heavier lines should
be drawn to the front of the subject as in
accepted art practices, with the lighter
lines to the rear giving an illusion of
depth or roundness to the drawing.
This illusion of depth in the first draw-
ing can be intensified to advantage in this
type of work. A good stereo drawing is

288

October 1952 Journal of the SMPTE Vol.59

4 FT. STEREO
SCREEN OP PLANE

Figure 2

finished when a satisfactory delineation
of the subject is obtained in the rather
stiff and hard-outlined techniques pecu-
liar to animation. In this process the
first drawing is always called "L," or
"the left-eye drawing" for convenience
and to avoid confusion when many draw-
ings are at hand.

Figure 2 is an extreme example with an
extra-large subject, and shows the ap-
proach to the second stereo drawing
while illustrating the first step in sketch-
ing a 2-ft transparent cube as it would
appear in stereo from a distance of 3 ft
to the artist; the focal point selection is
dead center. The picture is to be shown
on a 4-ft screen. The L and R eyes are
placed at scale distance in scale inches
apart below a cross section of the subject.
(FP is the floor plan of I, the completed
left-eye drawing) . Vertical lines of sight
to infinity show where points of vision
cross the window-plane, or screen. MN
and MF are the "maximum near," and
the "maximum far" limits which can be

drawn with the point focus in the center
as indicated without causing eyestrain or
ghost images. These limits increase as
the distance from the artist to the subject
is increased, and it is obvious that as
these limits increase so does the depth of
the entire picture. Infinity backgrounds
may be added to assist further in depth
perception. MN is exactly halfway
between the window-plane and the ob-
server, while MF is the same distance on
the other side of the plane. Lines
marked * are the outside limits of the
picture as a whole, and run from the eyes
to W — the edges of the picture or win-
dow-plane. MN and MF will always
place L and R 2f in. apart on the
window-plane.

Lines drawn from L and R through the
subject area and crossed at the point of
focus (1), will indicate the amount of
shift (2), or line displacement, necessary
for both near and far stereoscopic effects
within the cross section.

Ernest F. Hiser: Animation and Stereo Processes

289

POINT
SHIFT

Figure 4

PUNCH SHIFT FOR

SINGLE PLANE BACKGROUND

USE OPPOSITE
SHIFT FOR CELL
FOREGROUNDS

For further simplified operation, Fig. 3
shows that the amount of shift can be
estimated quickly by a simple crossing of
the L sight line at the point of focus by
the R sight line. All points to the front

of the focal point, as well as those at the
rear are to be offset in exact proportion
to the width of the shift-cross or scale,
and in the direction of the corresponding
arrows A and B. It is obvious that this
shift will be greater or narrower in width
as the distance L and R is nearer or far-
ther away from the window-plane or fo-
cal point. Lines (a) and (b) are a re-
minder of the maximum separation that
can be made for near and far objects.

Figure 4 illustrates a simple object with
exaggerated drafting for easy visualiza-
tion of the mechanics of the shift-scale,
and brings the problem to completion for
both L and R drawings. A is the orig-
inal, or L, drawing. B is the cross sec-
tion of the object with exaggerated shift-
scale in place and with all major points
projected over to the right where the
cross section is duplicated. Point shifts
are measured in accordance with the pro-
portional widths of the shift-scale, and a

290

October 1952 Journal of the SMPTE Vol. 59

Figure 6

new, or right-eye cross section is super-
imposed over the L cross section. Lines
are projected down from all points to
complete the R stereo drawing.

Additional cross sections should be
made of any part of the subject which
changes contour, and from which point
shifts can be measured from the shift-
scale. It is possible when drawing con-
sistently on the same distance scale (as in
animation) to estimate the R shifts on
either side of the point of focus by the eye
alone with considerable accuracy, as
soon as the near and far shifts of the scale
are known for the object being drawn.
Exaggerations for special emphatic effects
in both near and far points of interest can
be obtained by increasing or decreasing
the shift-scale measurements to unbal-
anced amounts. The shift-scale should
be drawn in perspective as in the subject
when the scene is large enough to include
noticeable perspective.

When a flat-plane background is to be
located at any point between the back
limits of the subject and infinity, only one
drawing is necessary. In this case the
paired L and R drawings are made on
cells for use over the single-drawing back-
ground. This background will need a
stereo-shift in proportion to the desired
depth in the scene which is accomplished

on a standard animation board, as in
Fig. 5. The background paper is
punched twice to proper offset measure-
ments for the L and R image shift and is
used underneath the corresponding cell
to complete either the L or R assembly.

Subject parts may be labeled at their
different stereo levels, and flat-plane fore-
grounds and details may be added in this
manner to complete a scene without
working on the main L and R drawings.
The labels or details are drawn on cells
which are double shift-punched for the
correct plane, and are placed on top of
the background and L or R assembly for
photographing.

Figure 6 is a scientific stereo drawing
made with a back mount for the subject
simulating a background, a device which
sometimes assists the observer in obtain-
ing good stereo vision. Figure 7 is a
drawing without a supporting back-
ground, and in this case the stereoscopic
effect depends entirely upon the shift
drawn in the R-eye drawing. Actually,
the R drawing is the only one where
depth measurement and shift are neces-
sary. Entire animation sequences can
be drawn first as for regular animated
films, can be checked for timing and
accuracy, and be otherwise completely
finished before the R-eye series is begun.

Ernest F. Hiser: Animation and Stereo Processes

291

Figure 7

In cases where old two-dimensional films
can be shown to advantage stereoscopi-
cally, the original drawings can be used
as the entire L series.

The process of photographing the com-
pleted stereoscopic drawing assemblies
depends upon the equipment available
and the aims of the project. As there

are several good procedures, the one cur-
rently in use will provide the method
necessary to turn the completed work into
practical commercial, teaching or lecture
material.

Reference

1. Norman McLaren, "Stereographic ani-
mation," Jour. SMPTE, 57: 513-520,
Dec. 1951.

292

October 1952 Journal of the SMPTE Vol. 59

nimation for
Individual Television Stations

By ERNEST F. RISER

With the advent of television and the consequent increased use of the animated
film for advertising, it has become necessary to devise quick and inexpensive
methods for the small studio to produce such films. In this paper some
simplified techniques for animation are described.

JL HERE is no need to discuss or evaluate
the use of animated films as an advertis-
ing or spot-announcement medium.
The problem is, how can such work be
produced by the average small studio
art department at a time and price
ratio that will allow for speed, re-
vamping, and the visual appeal necessary
for local and short-contract sponsors?
Farming out films to commercial firms
with their expensive production methods
may be desirable but is out of the
question unless the sponsor or depart-
ment contemplating the work is fortunate
enough to have funds warranting such
productions. Simpler and cheaper
methods of animation must be devised
if this medium is to be utilized to full
advantage.

No claim is made for extensive
originality in presenting these animation
techniques. This paper was primarily

A contribution submitted on June 25,
1952, by Ernest F. Riser, Dept. of Medical
Illustration, School of Medicine and
University Hospitals, The University of
Oklahoma, Oklahoma City 4, Okla.

designed to present routines capable of
producing usable film material as
speedily as possible. Comparatively
simple or simulated animation can be
prepared after one has made a study of
"stop-motion" — the basis of all anima-
tion. Throughout this paper, the term
"animation" will be used to indicate all
phases of stop-motion.

The staff artist does not need to be a
photographer to do animation, as the
photographic part of the process is
mostly a fixed thing, and all camera
operations necessary for the methods
used are easily applied. Figure 1-(1)
shows a simple camera stand with an
interchangeable animation board which
will work equally well under the camera
and over the illuminated tracing table.
Using the same board for two purposes
will also eliminate error in register and
layout.

It is well to remember that the effect
of animation is the aim, rather than true
animation, and that the effect processes
cannot encompass some types of fluid
motion. To obtain smooth motion in
human and animal figures, or similar

October 1952 Journal of the SMPTE Vol. 59

293

Fig. 1-(1). A, animation stand complete; B, animation board on pegs under camera
(the same peg holes fit on tracing table at right which is illuminated by circular
lamp); C, camera; D, lamp under animation stand for transillumination; and £,
transformer for laps, fade-ins and fade-outs.

Fig. l-(2). Method of drawing on paper with cell overlay.

complicated multiplaned objects, draw-
ings such as those made by commercial
animators will have to be approximated.
Although it is possible to simplify these
units to a great degree, too much
simplification will produce an effect so
amateurish that an entire sequence may
be spoiled.

The "story" of the action, whether
it be for a chart, graph or complicated
pictorial delineation must first be broken
down into scenes or action units as one
would imagine them on the screen:
titles, sound, action, etc., in proper
order. Along one side of this script
little sketches are made at each change
of scene or action tempo. These assist
in visualizing the film, and form a basis
for determining the overall mechanics
of timing and the animation methods to

employ. This layout is called the
"storyboard" (Fig. 2).

The artist "times" the action by
imagining that action as taking place,
even going so far as to draw rough graph
lines and details as he would have them
appear for each little sketch on the
storyboard. With the help of a stop
watch he marks the times obtained in
seconds on each sketch, as well as after
each legend, rest and title. The sound-
track wordage is also timed and balanced
against the animation timing at this
stage of the production. The artist will
now be able to add "holds," or places
where the action stands still, to his
script while commentary wordage con-
tinues. It is seldom necessary to have
continuous action throughout a se-
quence, in fact, holds are desirable for

294

October 1952 Journal of the SMPTE Vol. 59

12- Storyboard- RADIOLOGICAL SAFETY.
Scene Commentary-Action

Scl5-

Scl5

6 Are

ce//s

015 -'THE BOMB EXPLOSION AS AT HIROSHIMA FORMS
A BALL OF FIRE APPROXIMATELY ONE THIRD
OF A MILE IN DIAMETER, WITH A TEMPERATURE
OF 100 MILLION DEGREES FAHRENHEIT, AND IS ..
SIMILAR TO A SMALL PIECE OF THE SUN1 H/\ 0

A15 - Drg. showing 'peaceful city' skyline

ClJa-'A TERRIFIC SHOCK WAVE WITH WIND VELOCITIES
OF 500 to 1,000 MILES PER HODR, AND THE
EMISSION OF GREAT QUANTITIES OF RADIATIONS
MORE INTENSE THAN X-RAYS FOLLOWS THE BLAST'

A15a- Blast animated with 'radiations', etc /fid

C15b-' OFFICIAL FIGURES SHOW THAT AT HIROSHIMA
THE BLAST KILLED AND DISABLED 260 OF ITS
300 REGISTERED PHYSICIANS; 1,800 OF ITS
2,400 NURSES AND FIRST-AID WORKERS;
DESTROYED 26 OF THE 33 FIRE STATIONS ,
AND ALL OF THE HOSPITALS. A LARGE NUMBER
OF PERSONS DIED LATER FROM INTERNAL BURNS
CAUSED BY THE RADIUM-LIKE EMISSIONS FROM
THE BLAST. THESE RADIOACTIVE FISSION
PRODUCTS OF U235 LIBERATE ALPHA, BETA,
AND OAMMA RAYS, AS WELL AS NEUTRONS'

L22 - INJURIES EXPECTED

(Legends fi-fo giving injury figures)

EXTERNAL BODY RADIATION IS SIMILAR TO THE
EXPOSURE FROM A GIANT X-RAY MACHINE , EXCEPT
THAT THE RAYS COME FROM ALL DIRECTIONS.
THE MAXIMUM PERMISSABLE EXPOSURE IS BASED
UPON 'TOTAL BODY RADIATION' . EXPOSURES OF
10-25r MAY PRODUCE SMALL INJURIES, 25-100r

SOME INJURIES, 100-30Or WILL RESULT
^ Jttfll30Qr JENSA FATAL

Fig. 2. The storyboard, with working data and times computed.

visual observation of scenes showing a
sponsor's product, etc.

The amount of film necessary for the
production can then be estimated from
the total number of seconds or frames
obtained. As sound film is projected
at the rate of 24 frame/sec, the number
of drawings required and the measure-
ment of line displacements necessary
for smooth motion can also be calculated
from these timing figures. Some action
speeds or drawing advances will require
a two-frame exposure for each drawing,
while others will use more or less ex-
posures for smoothness of action. Cau-
tion must be used in the preparation of
the exposure figures: it is very easy
accidentally to clip off a few words of
commentary, or to allow action to

proceed too fast — or to drag along —
upon the television screen.

Drawings for television should be
made on paper which has a decided
tone, so that unpleasant smears will not
occur on the screen. On all work of
this kind, pure white of any type should
be used sparingly if at all. The art
work should be somewhat stiff and hard,
with considerable emphasis on contrast.
Soft, delicate drawings may be used for
background work in some instances,
although detail cannot be followed
easily by the viewers when this type of
art is in motion.

Every phase of motion in the story
need not be animated. When the
action is very obvious, such as in the
opening of a package, gadget manipula-

Ernest F. Riser: Animation for Television

295

tion, or the placing of many objects in
the scene, numerous drawings can be
avoided by fading-in the change with
laps or dissolves. A little arrow or
other indicator pointing to the ap-
proaching fade-in phase area will focus
attention on the spot so that the desired
eftect will not be missed. It is possible,
with much hard work and many draw-
ings, to produce such fancy and intricate
animation at a critical point that the
subject matter is lost to the observer.

Examples of simple animation can be
demonstrated by a conventional display
ad or catalog layout, i.e. a drawing with
several legends and indicator lines upon
it as follows:

a. The drawing is to appear first without
catch lines. These appear singly with a
little arrow pointing to the corresponding
area. Each legend and its arrow vanishes
for a second or two before the next legend
appears. . . . This effect is obtained by
the use of little lettered cards for the
legends and a single cutout arrow which
are placed in position on the drawing
before each exposure. Rests of one or
two seconds are exposed between the
legends. A piece of clear plate glass is
placed over the assembly during exposure
to make the items lie flat and smooth.
Single-frame camera work is not necessary
unless the number of frames exposed must
be exact.

b. The drawing is again to appear first
without legends. This time the legends
appear singly as before but remain in the
scene once they appear. Corresponding
indicator lines run from each legend
directly to the point in question. In this
case the lettering and lines are done on a
celluloid overlay, or "cell." This cell is
put in register over the drawing so that
the assembly appears complete, as at the
end of the sequence. The drawing is
placed upside down under the camera,
and the scene is photographed backwards,
that is, by scratching off the lettering and
lines from the cell one at a time with a
blunt point while reading the timing
figures on the storyboard in reverse order.
The artist ends with only the drawing
remaining under the blank cell. After
this section of film has been processed it

is reversed (turned end for end) for pro- fe
jection, and the effect will be as desired.

c. Dotted or solid lines encircling any p
particular area on the drawing for em- I
phasis may be made to appear by this cell- I
and-reversal method either by "flashing- I
in" the line as a whole, or by causing the I
line to "draw itself in," which is accom- I
plished by scratching out only a small I
portion of the line at a time while using I
evenly timed single-frame camera ex-
posures. Again, the timing or exposure
sheet is read in reverse for correct filming
and effect.

Basic graph or chart forms and photo-
graphs may be used instead of drawings
for the master background, and lines,
lettering, figures, etc., may be made to
appear as desired by this method. Two
cells can be used over a background at
the same time when separate action
lines cross each other or when the
subject matter is more complicated.
Scratchboard can also be used for the
background when additional scratch-
off work is necessary. The animator
can visualize many variations of this
process to apply to any story situation
if he will take the trouble to lay out and
time a sample storyboard for a sequence
which is to appear as above.

Layouts using black backgrounds are
sometimes permissible for various types
of work, especially when light or colored
lines and lettering constitute the bulk
of the copy. A good black is not always
easy to get from a photographed card;
and painted-out, scratched-out or
covered-up lines are apt to show up
as such. One way to avoid this trouble
is to make the original layout in black
on white paper. A litho negative is made
of this drawing in the proper size for
animation. Lines, detail and copy are
drawn with transparent color as desired
on this negative. It is placed in upside-
down position under the camera as
before, with a lamp underneath the
transparency ready for transillumina-
tion. All top lamps are switched off.
The lines are then painted out in reverse

296

October 1952 Journal of the SMPTE Vol. 59

storyboard order with a matte black
watercolor. This process gives a true
black background with brilliantly colored
detail, and will show no evidence of
construction upon construction. Such
work when photographed on color film
will produce the necessary grays for
black-and-white television projection and
will also provide a film for future color
television.

It is a good idea when working in
color for black-and-white projection to
photograph a frame or two of each color
in the brand of paint used and make a
gray scale from these tests. As few
colors photograph exactly as they appear
on a card or on celluloid, this test will
also serve as a guide for art work de-
signed to be shown in color.

The above method is also invaluable
for fast, easy production of line diagrams
or pictorial "growths" when a black
background can be used. It is also
valuable for title work and designs
which "draw themselves." In title
work using color, the black background
can be changed to any color desired by
winding color film already exposed for
the title back in the camera to the be-
ginning of the title and double-exposing
a piece of colored paper over the shot
already made. A good paper to use
for many effects in animation is artist's
pastel velour, which will not reflect
highlights because of its matte surface.
During photographing, the transillumi-
nation lamp is, of course, turned off
and the top ones turned on. This
method is limited only by the animator's
imagination, and will produce many
color effects from any black-and-white
original.

Cutout overlays may be utilized in
many ways to supplant a drawing,
photograph or chart, and to add interest
or detail to any type of scene. These
cutouts must be made accurately to
register exactly with the drawing under-
neath. Cutouts should be made on
opaque paper and have their edges
blackened before use. To register cor-

rectly, cutouts are cemented to acetate
cells with rubber cement, which will
not cause wrinkles or waves in the cell.
When registered on a regular animation
board with its registering pins, assembly
will be easy and successive phases will
match line for line. Legends and
indicator lines may be inked in on the
same cell as the cutout.

The first form of animation as in-
vented by Winsor McKay consisted of
a series of drawings with subject and
backgrounds complete, and with action
similar to the little "flip" books for
children. This type of animation was
very difficult and time-consuming, as
tracings of all lines had to be extremely
accurate in all parts of the drawings.
In this type of work the lines and detail
which stood still for some time were
subject to a definite "shimmy." A
variation of this process is still used
when every part of a drawing is under-
going a continuous change.

Fluid-motion animation is best
handled in pen-and-ink outline with
considerable contrast in shading or
coloring. Any part of the drawing
which does not move, even for a short
time, should be made on a cell to
eliminate work and stabilize the action.
When no background is needed, the
action is drawn on toned or colored
sheets of paper plus the required number
of work-saving cells. When the back-
ground is an inherent part of the scene,
or continuous fluid motion is required
over a combination layout, all action is
drawn on cells. The lines and outlines
are inked in on the front of the cell, and
opaque color is painted within the
outlines from the back, which preserves
the sharpness of the inked lines and
provides opacity to the cell. Action
may be drawn on paper and transferred
to cells as in the cutout method if
desired, since the results will be the
same (Fig. l-(2)).

In animating any action the "ex-
tremes" — the first and last drawings of
the scene or action phase — are sketched

Ernest F. Hiser: Animation for Television

297

first. A study of the action will then
show which parts of that action will
require emphasis or near-stops between
the extremes. With these drawings
made, the animator then has the first
and last drawings as well as the major
in-betweens of the contemplated action,
and the assembly will appear as a series
of drawings showing the major phases
of a subject such as might be prepared
for publication in an advertisement or
article.

The storyboard will then show how
much time is to be consumed between
these majors. Dividing the times ob-
tained into frames will give the proper
line displacements or advance necessary
on each drawing for correct and smooth
action, as well as the final number of
drawings required to fit the action. It
is well to keep in mind the fact that the
more drawings there are to be made for
a certain action (involving the least line
displacement) the smoother that action
will be. If the number of drawings
actually required is considerably de-
creased, line-displacement distances on
consecutive drawings must be increased
and a greater number of frames exposed
for each drawing. These increases
Can easily result in a very jumpy se-
quence.

Slow or gradual changes are generally
preferable in advertising and lecture
films, and, at sound speed, a J-in. line
advance with a two-frame exposure on
a drawing which has a working field of
approximately 8 X 10 in., is about the
greatest advance which can be made
between drawings without obtaining
an irritating jumpiness. Even this does
not appear too smooth at times when
great contrast is encountered in art
work. A J-in. advance with a single-
frame exposure will have much smoother
motion, although the tempo might be a
little fast. It is always better to make
a few extra drawings than to have the
action pass by too quickly or shimmy
badly because of excessive exposures.

After the majors and in-betweens are
prepared the drawings are checked for
all lines and components which will
stand still for any length of time during
the action. These lines are drawn on
cells for stabilization and elimination
of shimmy. Although regular com-
mercial animators use a complicated
three-cell arrangement it is seldom
necessary to go beyond one cell for
simplified advertising and spot films.
When even one cell is used over a
background or for work-saving reasons,
it will be necessary to expose all drawings
of that series through the same number
of blank cells before and after the cells
are used because of the extra tone
imparted to a scene by any cell overlay.
After the cells are made, the extremes,
majors and in-betweens on paper are
inked in (minus the lines on the cells).
In finishing the in-betweens it is not
necessary in fairly rapid action to obtain
the same degree of exactness in drafts-
manship as on the majors, although the
line displacements must be accurate.

Each drawing is then marked as to
consecutive number in the scene, number
of exposures required, the number of
the cell which must accompany it, and
any other data considered important
to the animator.

To eliminate excessive background
area, or to localize action or interest,
a foreground can be made of colored
velour paper with a round or otherwise
suitable opening in it for the action to
show through. This foreground is
placed over the drawing assembly on
the registering pins before exposure of
the scene.

The above basic production methods
are as near to actual commercial anima-
tion as the television animator needs to
go for the production of ordinary local
film needs, and by using one or all of
the above — even in one sequence when
they will blend together — much valu-
able material can be designed. The
effect or presentation of the subject is
all that matters; the manner of obtain-

298

October 1952 Journal of the SMPTE Vol. 59

ing that effect is secondary as long as
the methods employed do not result in
a visual hodgepodge of artistic media
without advertising or story value.
Once more, the entire effort depends
upon the design of the storyboard —
the blueprint of the production. If
the storyboard has been carefully drafted
with full regard to the story, and timed
with a view to good presentation, an
overall technique will become apparent
which includes one or more of the above
processes of simplified animation. The
method using the least amount of art
work should be selected whenever

possible, as in many cases the simpler
technique will present the subject more
graphically than will the complicated
one.

Animation should only be used when
the subject cannot be presented by
regular photography, or when a new
method of approach, unusual effects,
or the presence of artistic values can
play an important part in the instructive
aspects of the advertisement or story.
Animation should also be used as an
adjunct rather than as the principle
illustrative medium unless the entire
subject benefits by graphic animated
pictorialization.

Ernest F. Hiser: Animation for Television

299

X-ray Motion Picture Techniques Employed
in Medical Diagnosis and Research

By S. A. WEINBERG, J. S. WATSON, Jr., and G. H. RAMSEY

With Appendix by W. E. SGHADE

X-ray motion picture techniques are reviewed with attention to relative
exposure requirements and ability to record detail. Direct cineradiography
on full-scale screen-films provides the best reproduction of detail but does not
at present reach true motion picture speeds. Cinefluorography is the most
flexible and least expensive of the traditional methods. Because of harmful
effects of radiation cinefluorographic examinations of human subjects must
generally be limited to a relatively few seconds. The length of examinations
can be much prolonged with the help of screen image intensification. Un-
fortunately the x-ray motion pictures made by kinescope recording are not
yet satisfactory from the point of view of detail.

-1- HERE ARE a number of ways of
making x-ray motion pictures, each one
of which has its special virtues and limi-
tations :

1. Successive frames of film are
exposed directly to the x-rays which
have passed through the subject.

2. Instead of being exposed directly

Presented on May 2, 1951, at the Society's
Convention at New York, by S. A. Wein-
berg, J. S. Watson, Jr., and G. H. Ramsey,
Dept. of Radiology, University of Roch-
ester School of Medicine and Dentistry,
260 Grittenden Blvd., Rochester 20, N.Y.
This investigation was supported in part
by a research grant from the National
Heart Institute of the National Institutes
of Health, Public Health Service. The
anpendix was contributed in June 1952
by W. E. Schade, Hawk-Eye Works, East-
man Kodak Co., Rochester, N.Y.

to x-rays, each frame of double-coated
film is compressed at the moment of
exposure between a pair of fluorescent
intensifying screens. Excited by x-rays,
the screens emit violet and blue light,
thus exposing the film.

3. A fluorescent screen is set up per-
pendicular to the x-ray beam as in
fluoroscopy. The image formed on the
near side of the screen is copied by a
motion picture camera to a much re-
duced scale.

4. The screen image is picked up by
a television camera, and a kinescope
recording is made of the action. This
method is still in the experimental stage.

Direct Cineradiography Without
Intensifying Screens

Methods 1 and 2 are generally re-
ferred to as direct or full-scale cineradi-

300

October 1952 Journal of the SMPTE Vol. 59

ography. In both cases the shadow
image on the film is a little larger than
the subject; and in this respect the
methods are alike. There is, however,
a striking difference between them in the
matter of photographic speed. Mainly
because of the poor absorption of hard
x-rays by the film emulsion, an exami-
nation recorded on single-coated film
without screens, at diagnostic kilovoltage
levels, may require 25 or 50 times as
much x-ray intensity as a similar exami-
nation recorded with the aid of intensify-
ing screens. Method 1 is, in fact, so
"slow" that its use is confined to small,
easily penetrable subjects of thin cross
section. The subject, a worm or insect,1
the thorax or abdomen of a mouse,2
is positioned in front of the aperture
of a 35mm camera, and the x-ray beam
is directed through the subject to the
film. During the pulldown phase of the
camera the film must be protected from
x-ray fogging, either by reinforcing the
shutter with lead or by interrupting the
primary circuit of the x-ray generator.3
It so happens that the ability of the un-
aided film emulsion to resolve fine detail
is relatively very good. This is for-
tunate, because the significant detail
of small subjects approaches the micro-
scopic.

Direct Cineradiography With
Intensifying Screens

With the aid of intensifying screens
direct cineradiography becomes a much
"faster" technique and can be applied
to much larger and denser subjects. The
size of the film frame may be anywhere
from 5 by 5 in. to 12 by 15 in., the latter
size being large enough to include an
adult chest. When properly exposed,
the so-called screen-films are recognized
models of radiographic quality and
would appear at first glance to be an
ideal, if rather expensive, medium for
making x-ray motion pictures of human
subjects. Unfortunately it is not easy
to impart rapid intermittent motion to
large strips of film. Machines have been

designed with the hope of making 12 or
1 6 pictures/sec, but few, if any, of them
can be counted on to function at more
than 4 or 5 pictures/sec without frequent
breakdowns.4 The necessity for sand-
wiching each frame of film closely be-
tween fragile screens at the instant of
exposure makes the problem doubly
difficult. Both film and screens pick
up multiple scratches, dust and frag-
ments collect at the aperture, and, worst
of all, poor contact between screens and
film results in grossly unsharp pictures.

The most successful attempts at full-
scale cineradiography at true motion
picture speeds have been made on con-
tinuously moving 15-in roll film exposed
to extremely brief pulses of radiation.
The single-coated film passes over an
idle roller surfaced with a low-lag
phosphor, the film being thus exposed
in contact with what amounts to a single
intensifying screen. With an experi-
mental condenser discharge apparatus,
as many as 100 exposures/sec have
been made in this way.

As a rule, however, the motion studies
made by method 2 are not true x-ray
motion pictures, but simply rapid serial
x-rays exposed at from 1 to 5 pictures/
sec. Rapid serial x-rays have been
much in demand in the past few years
for making contrast studies of various
parts of the circulatory system. The
negatives are read as stills, although it
is perfectly possible to copy them in
sequence on motion picture film, and by
repeating each negative frame three or
four times on the print, to turn out a
rather jerky motion picture.5

Cinefluorography

The great majority of true x-ray
motion pictures are made by method 3,
generally known as Cinefluorography or
indirect cineradiography. Here we have
an economical and flexible technique for
examining subjects of medium and large
size at camera speeds up to 120 frames/
sec. The faults of the method are,
first, a less favorable exposure factor

Weinberg, Watson and Ramsey: X-ray Motion Pictures

301

•a

302

October 1952 Journal of the SMPTE Vol. 59

than that of direct cineradiography with
screens, and second, a considerably
greater degree of inherent unsharpness,
as can be seen from the comparative
figures given in Table I. It must also

Table I. Exposure and Unsharpness*

Characteristics of X-ray
Motion Picture Techniques

Relative

exposure Unsharp-

require- ness* or

Method ment blur, mm

1 . Direct cineradi-
ography (without

screens) 25.0 0.05

2. Direct cineradi-
ography (medium

speed screens). . 1.0 0.3

12 by 16 in. E2

screen, //0.85

lens, ortho film 2.0 6.0

3. 35mm cinefluor-
ography 10 by 13
in. E2 screen, //

1 .5 lens, ortho film 8.0 3.0

4J by 6 in. D

screen, //1. 5

lens, ortho film 16.0 1.5

* The unsharpness values listed above
are offered as rough estimates and may
contain a fairly large error. It is par-
ticularly difficult to give a satisfactory
overall unsharpness value for the 35mm
frame because of the wide difference be-
tween lens performance at the edge and in
the center. For a constructive criticism
of traditional sharpness and resolution
measurements, see the recent paper by
Higgins and Jones.6

be admitted that the single-coated
motion picture film is inferior in con-
trast to double-coated screen-film.
About the only remedy for this condition
is the frequent use of a stationary grid
to increase contrast by reducing scatter.
If sufficient radiation could be brought
to bear, it would no doubt be possible
to make 35mm cinefluorographic records
displaying nearly as much subject detail
as 35mm reduction prints from full-scale

screen-films. There is, however, an
upper limit to the amount of continuous
or near-continuous radiation that can
be provided by the x-ray machine, and
this limit must be further reduced when
dealing with human subjects. Subject
thickness, camera speed and length of
examination in seconds must all be taken
into account in budgeting permissible
radiation, often leaving little room for
the niceties of good copying. The
desirably sharp tungstate intensifying
screen, to which routine screen-films
owe much of their excellent definition,
is replaced in cinefluorography of adult
human subjects by a faster, less sharp
screen coated with relatively coarse
crystals of zinc cadmium sulfide. Then
the blurred image formed on the un-
sharp screen is copied, blurs and all, by
an ultrafast lens (definitely not a process
lens) which in turn contributes addi-
tional blur and flare of its own.

As an illustration of what happens to
fine subject detail under these extreme
conditions we have reproduced side by
side in Fig. 1 a full-scale screen-film and
an enlarged 35mm frame taken from a
cinefluorographic record. In this par-
ticular case the improvement of 35mm
definition, which could have been ob-
tained by using a slower, better-cor-
rected lens or a slower, sharper screen,
was sacrificed in favor of a relatively
high camera speed. Figure 2 shows the
improvement of definition which results
from using a sharp screen in close-up
views. Curiously enough we have been
unable to obtain any appreciable in-
crease in sharpness by substituting a
finer-grain film for the fast green-
sensitive ortho film commonly used in
cinefluorography.

The //0.85 lens referred to in Table I
is the 55-mm Zeiss R-Biotar originally
designed for 16mm film, but used, for
want of anything better, on several
35mm cinefluorographic units including
our own (Fig. 3). With this lens at
full aperture, definition in the corners
of the 35mm frame is frankly ter-

Weinberg, Watson and Ramsey: X-ray Motion Pictures

303

» w

S g,

1.2

•a B
•

•

1 1

V _

b ^

« nfl
t)
en

•5s
°

•s-s
I"

<T5 "^

304

October 1952 Journal of the SMPTE Vol. 59

Fig. 3. Left, Kodak f/0.81 43-mm focal length lens mounted on Cine Kodak

Special. A popular f/1.5 lens is shown below for comparison. Right, Zeiss

R-Biotar f/0.85 55-mm focal length lens mounted on 35mm camera.

Fig. 4. New Kodak f/0.75 Fluro Ektar Lens designed for cinefluorography at a
magnification of 1:16 (U.S. Patent 2,604,013).

Weinberg, Watson and Ramsey: X-ray Motion Pictures

305

rible. The recent announcement of
two new refracting lenses designed
specifically for 35mm cinefluorography
promises better definition than can
be had from the 5 5 -mm R-Biotar, to-
gether with an increase rather than a
decrease of speed. The lenses are the
Wray 65-mm //0.71 and the Kodak
110-mm Fluro Ektar //0.75 (Fig. 4).
Constructional details of the latter lens
are described in the appended article
by W. E. Schade. Both lenses are
corrected for magnification of 1:16,
that is, for a screen area a little smaller
than 12 in. by 16 in. They should
more than fill the place of the longer-
focus Leitz and Zeiss //0.85 lenses,
manufactured at one time for 35mm
cinefluorography, but unobtainable since
1940.

X-ray Motion Pictures
by Kinescope Recording

The fourth method of making x-ray
motion pictures has emerged as a by-
product of recent experiments in fluoro-
scopic screen intensification. Of the
various image tubes and other devices
which have been developed for this
purpose the only one at present adaptable
to motion picture work appears to be the
Johns Hopkins apparatus demonstrated
by Morgan7 in 1950. In Morgan's
intensifier the fluoroscopic image is
picked up by a television camera fitted
with an //0.7 Schmidt optical system of
the "folded" type sometimes seen in
television receivers. The reason for
using such an extremely fast objective
at the input end of the television ap-
paratus is, of course, to make the most of
the low brightness conditions prevailing
on the fluorescent screen at average
fluoroscopic x-ray intensities. It is now
generally agreed that during fluoroscopy
the near point on the subject's skin
should not receive more than 10 r/min,
a dosage rate frequently reduced to
3 r/min or less by increasing filtration
of the x-ray beam and using higher peak
voltage across the x-ray tube. At these

comparatively low intensities the bright-
ness of the fluoroscopic image rarely
exceeds 0.03 ft-mL (foot-millilamberts)
in the highlights, and may fall below
0.001 ft-mL in the shadows. That
such an image can be picked up at all
indicates the remarkable sensitivity of
the image orthicon tube.

As it appears on the kinescope, the
intensified image of the subject is said
to have an average brightness of about
3 ft-mL, and is therefore, according to
Morgan, from 300 to 3000 times brighter
than the original fluoroscopic image.
Like other kinescope images it can be
copied at 30 frames/sec without resort
to high-contrast film or lenses of aperture
greater than //1. 5.

By way of demonstrating the motion
picture possibilities of his intensifier,
Morgan has made a kinescope recording
of a barium enema examination of a
child of 7, covering about 3 min of
action,7 during which time the subject
is said to have received a total skin
dose of only 20 r. If it were attempted
to record a similar examination by
routine cinefluorography (//0.85 lens,
E2 screen, stationary grid to reduce
scatter, camera speed of 30 frames/sec),
the total dose of 20 r would be reached
in about 10 sec; in other words, only
about 1/18 of the 3-min examination
could be recorded. Of course, by re-
ducing camera speed to 7.5 frames/sec
(and repeating each negative frame on
the print) the 10 sec of recorded action
could be stretched to 40. Indeed, it
would be possible by substituting the
Fluro Ektar //0.75 lens for the //0.85
R-Biotar to prolong the take to 50 sec,
but even so a more than three-fold
advantage would remain with the kine-
scope record.

As can be imagined from the number
of glass and electron optical stages
involved in x-ray kinescope recording,
the motion picture films made by
method 4 are not at present satisfactory
from the point of view of detail. To
what extent this condition can be im-

306

October 1952 Journal of the SMPTE Vol. 59

proved remains to be seen. Certainly
there is enough demand for better
fluoroscopy, not to mention better
image tubes and better television, to
insure that the problem will not be
neglected.

References

1. H. F. Sherwood, "Soft x-ray motion
pictures of small biological specimens,"
Jour. SMPE, 28: 614-618, June 1937.

2. R. Janker, "Roentgen cinematog-
raphy," Am. J. Roentgenol. Radium
Therapy, 36: 286, Sept. 1936.

3. J. S. Watson and S. Weinberg, "An
Improved Camera Drive for Cinefluorog-
raphy," 1949. Multigraphed copies
available from Department of Radiol-

ogy, University of Rochester School of
Medicine and Dentistry.

4. W. G. Scott, "The development of
angiocardiography and aortography."
Radiology, 56: 485, Apr. 1951. (Para-
graphs on radiographic equipment.)

5. A. E. Barclay, K. J. Franklin and M. L.
Pritchard, The Fetal Circulation,
Charles C. Thomas, Springfield, 111.,
1945, Chapter 2.

6. G. C. Higgins and L. A. Jones, "The
nature and evaluation of the sharpness
of photographic images," Jour. SMPTE,
58: 277-290, Apr. 1952.

7. R. H. Morgan and R. E. Sturm, "The
Johns Hopkins fluoroscopic screen in-
tensifier," Radiology, 57: 556, Oct. 1951.

8. R. H. Morgan (an interview), "Now:
motion pictures by x-ray," Johns
Hopkins Magazine, 3: 14, Dec. 1951.

Appendix: A New Kodak f/0.75 Fluro Ektar Lens*
By W. E. Schade

The new Kodak Fluro Ektar lens,
f/0.75 of focal length 110 mm designed
for 35mm cinefluorography at a magnifi-
cation of 1:16, can be described as an
extended modification of the classical
example of simplicity, the Cooke triplet,
to which a negative field-flattening ele-
ment located near the focal plane has
been added. Alternatively, the system
could be regarded as a modified Cooke
triplet to which a telephoto system has
been attached.

However, since simplicity and the
application of a field-flattening element
have been the leading motives in the
design of the lens, the following detailed
explanations will pertain to the first
description.

The//0.75 Fluro Ektar lens consists
of seven glass elements, two of which are
made of the new high-index glasses
developed and manufactured by East-
man Kodak Co. (Fig. 5).

The Appendix was contributed in June
1952 by W. E. Schade, Hawk-Eye Works,
Eastman Kodak Company, Rochester,
N.Y.

*U.S. Patent, 2,604,013, Aug. 8, 1951.

The first two elements (1 and 2) are
of collective power. These are followed
by a hyperchromatic component of dis-
persive power. The negative element
(3) of this component is made of a
highly dispersing flint glass, whereas
the other element (4) of this component
consists of one of the new high-index
glasses mentioned above. The proper-
ties of these two glasses, namely, nearly
equal high indices of refraction for the
D line, but widely differing dispersions,
have made it possible to simplify the
achromatization of the new lens.

Elements 5 and 6 are again of collec-
tive power, element 6 being made of
one of the new high-index glasses.

The arrangement of these six elements,
as shown in Fig. 5 produces a focal length
of 106.4 mm and the marginal ray
emerges at an aperture of //0.64.

Finally, the field-flattening element
(7) of dispersive power, located near the
focal plane, then extends the focal
length to 110 mm and reduces the aper-
ture to f/0.75 as required.

The results of this relatively simple
design are such that the lens will render

Weinberg, Watson and Ramsey: X-ray Motion Pictures

307

Fig. 5. Cross section of Kodak f/0.75 Fluro Ektar Lens of 110-mra focal length
designed for 35mm cinefluorography (U. S. Patent 2,604,013).

highly satisfactory performance in many
applications. The spherical aberra-
tions have been reduced to an extreme
minimum. Astigmatism and curvature
of field are practically eliminated and
the distortion (barrel) is negligible.
The color corrections, longitudinal as
well as lateral, are also fulfilled.

The dimensions of the system at a
magnification of 1:16 are as follows :

Distance from screen to

image plane 2023 . 1 mm

Object distance (from

screen to first surface

of lens 1807.8mm

Image distance (from last

surface to image plane) . 7.3 mm
Length of lens (from first

to last surface) .... 208 . 0 mm
Diameter of front aperture . 143.2mm
Since preliminary tests have proved
the exceptionally satisfactory perform-
ance of the lens, it is anticipated many
applications for it will be found in
other fields.

308

October 1952 Journal of the SMPTE Vol. 59

A Precision Color Temperature
Meter for Tungsten Illumination

By G. H. DAWSON, D. E. GRANT and H. F. OTT

A precision color temperature meter utilizing red and blue filters is described.
A special logarithmic diaphragm largely eliminates undesirable effects of
nonuniform response over the cell area and aids accurate setting of the red
filter standard at high intensities.

A OR MOST VISUAL or photographic
purposes extremely accurate measure-
ments of color temperature are not
necessary. In the film industry, how-
ever, color films must be evaluated
carefully to determine specifications
which will, under proper conditions of
exposure and processing, result in
uniformly good color balance. Conse-
quently, to remove test variability as
much as possible, it is necessary to know
and control within relatively close
limits the color temperature of the
tungsten lamps. A red-blue ratio is used
as an index of color temperature since
the radiation from a tungsten lamp
follows closely the spectral energy dis-
tribution of a blackbody.

It was found that the variability
within available meters was greater
than the allowable tolerances of the
tungsten source itself for testing purposes.
Such a relatively high instrument vari-
ability would not assure a sufficiently

A contribution submitted July 21, 1952,
by G. E. Dawson, D. E. Grant and H. F.
Ott, Color Control Div., Eastman Kodak
Co., Rochester 4, N.Y.

reliable determination of color tempera-
ture.

Variability in most commercially
available meters can be attributed to:

1. Differential diffusion of blue and
red light and vignetting. These errors
are most serious when the light is off
axis or when an extended source is used.

2. Nonuniformities in response from
one area to another of the cell, giving
different effective color temperature
readings at different intensities of illumi-
nation.

3. Difficulties in adjusting the instru-
ment to the red filter standard at high
intensities where the aperture over the
cell is small and its area is changing
rapidly when a direct linear diaphragm
is used.

4. A trigger arrangement for shifting
filters which moves the entire instru-
ment when actuated.

Description

An improved color temperature meter,
Fig. 1, utilizing red and blue filters has
been designed by the authors to give the
needed precision. Most important to

October 1952 Journal of the SMPTE Vol. 59

309

Fig. 1. Color Temperature Meter.

the increased precision is a specially de-
signed diaphragm which allows incident
light to be distributed over the cell
surface at either high or low intensity.

The essential elements of the instru-
ment, labeled to correspond to Fig. 2,
are:

a. The diffuser
c. The special diaphragm
b, d. Filters

f. Trigger arrangement for

switching filters
e. Photronic cell
i. Meter

g, h. Handle, including tripod
socket

In use, the color temperature meter is
pointed directly at the source to be
measured and the diaphragm ring ro-
tated until a standard reading is ob-
tained on the microammeter through the
red filter. The trigger is then depressed
and a second reading is obtained through
the blue filter. The color temperature

of the source can then be read from a
calibration curve. A scale could be
inscribed on the microammeter reading
directly in color temperature.

Diffuser, Cell and Meter

To keep the angular acceptance large,
as well as to maintain accuracy of the
instrument, an opal diffuser was put at
the extreme front of the instrument.
The metal parts, other than the dia-
phragm, were arranged so they could
cause no shadowing of the cell. In
addition, the diffuser-to-cell distance
was made as small as possible. The
diffuser chosen was an opalized cellulose
acetate on glass support. To remove
any effects of the blue-red diffusion
differential of the opalized glass, a pale
blue filter was placed between the
diffuser and the diaphragm. Areas of
the filter are cut away so that it gives
maximum compensation when the dia-

310

October 1952 Journal of the SMPTE Vol. 59

rfjn

a Diffusing Disk
b Correction Filter
c Diaphragm Leaves
d Red and Blue Filters
Photronic Cell
Trigger Assembly
Handle

Tripod Socket
D-C Microammeter

Fig. 2. Schematic side view of Color Temperature Meter.

.gm openings are large, but none
when they are small.

The cell used in the instrument is a

! Type 3RR Weston Photronic Cell

especially selected for low fatigue at

both ends of the visual spectrum. The

' meter is Model 731 Weston 0 to 30

microammeter.

Diaphragm

The special diaphragm (Fig. 3)
• utilizes six leaves (a), three on each side
' of a thin center plate (b) which by rota-
•i tion causes the leaves to move over the
j aperture or away from it. The leaves

and actuating disk are between two
outer plates. These plates support the
pins on which the pivot ends of the
diaphragm leaves can rotate. The dia-
phragm leaves have long, narrow tongues
which at full open position extend across
the circular diaphragm opening dividing
it into six pie-shaped openings. Since
the support pins for the leaves are
spaced at 60° intervals alternately in
one support plate then the other, the
tongue of one leaf at full open aperture
overlays the tongue of a leaf on the
opposite side of the actuator.

Dawson, Grant and Ott: Color Temperature Meter

311

Fig. 3. Color Temperature Meter dia-
phragm.

The means of moving a leaf is a
headed pin through a cam slot (c) in
the diaphragm leaf into the center
actuating member. As this member
is rotated to close the diaphragm, each
leaf moves inward, rotating about its
support pin, the rate being controlled
by the cam slots which are cut so that
the logarithm of the open area of the
diaphragm is proportional to the angle
of rotation of the actuating ring. The
logarithmic-type diaphragm ring facili-
tates accurate setting of the constant
red filter reading regardless of light
intensity. The leaves are so shaped
that the pie-shaped openings first narrow
abruptly as the diaphragm is closed,
then gradually change shape to form six
equally-spaced diminishing cat-eyes.
The undesirable effects of nonuniform

response over the cell area are thus
largely eliminated.

Filters and Trigger Mechanism

The filters used were Kodak Wratten
Nos. 38 A and 29. These were so
mounted that a thumb-actuated trigger
mechanism replaced the red filter
normally in the beam with the blue
filter. The thumb-actuated trigger
causes less instrument motion than a
finger-actuated trigger. The handle,
in the side of which the trigger is located,
is shaped to fit the hand and is under
the center of gravity of the instrument.
It also includes a tripod socket for
critical measurements. Although the
instrument is accurate with illumination
off axis, its sensitivity to intensity varia-
tions is still sufficiently critical so that
care must be exercised to move the
instrument as little as possible.

Precision

The color temperature meter was
calibrated against 1000- and 1500-w
lamps at 200 to 1000 ft-c. The pre-
cision of the instrument as normally
used is =t 5 K. As the angle of illumina-
tion increases from 30° off axis to the
angle at which a reading can no longer
be obtained, the precision decreases
gradually to ±10 K. The accuracy is
dependent chiefly upon the validity of
the calibrations of the lamps used as
standards.

312

October 1952 Journal of the SMPTE Vol. 59

Comparison of Recording Processes

By JOHN G. FRAYNE

The three common forms of sound recording may be classed as mechanical
(disk), photographic and magnetic. All three methods are in common use
today and each is employed in a field for which it appears to be peculiarly
fitted. The purpose of this article is to examine briefly the factors which
determine the fidelity of each method. By fidelity we mean how true the
tonal range can be reproduced, the amount and nature of harmonic distortion
present, the signal-to-noise ratio possible with each method, and the amount
of wow or flutter that may be expected under average conditions of repro-
duction for each recording process.

Disk Recording

Although there are other methods of
mechanical recording, such as embossing,
we shall confine our discussions on me-
chanical recording in this article to the
well-known circular flat disk method.
This type of recording remains the most
popular form for home entertainment
and is widely used in transcription radio
programs. One characteristic that
differentiates disk recording from the
other methods is the comparatively
higher mass of the moving parts involved
in making and reproducing the record.
The disk material must actually be cut
with a stylus having a high degree of
stiffness and a comparatively high mass.
Likewise on reproduction, disk record-

A technical editorial by John G. Frayne,
Westrex Corp., 6601 Romaine St., Los
Angeles 38, Calif. Reprinted by per-
mission of the Editor of The Institute of
Radio Engineers, from Transactions of the
IRE, Professional Group on Audio, PGA 6:
Mar. 1952, and PGA 7: May 1952.

ing involves the movement of a repro-
ducing stylus which in itself must have
considerable stiffness and mass. In
disk recording, the resonant frequency
of the recorder is usually considerably
below the highest recorded frequencies.
Since this necessitates recording through
the resonant range of the recorder, a
high degree of damping must be em-
ployed to remove the resulting resonant
peak. This damping, whether supplied
by mechanical means or electromagneti-
cally through some sort of feedback sys-
tem, results in a velocity of the recording
stylus which is constant and independent
of the frequency for a constant applied
force. This type of recording is known
as constant velocity and with the addi-
tion of pre-emphasis in the recording
circuit is widely used in cutting present-
day high-quality records.

Since the amplitude of the cut for a
constant applied force is inversely pro-
portional to the frequency in a constant
velocity recorder, it is customary to
record the lower frequencies or longer

October 1952 Journal of the SMPTE Vol. 59

313

wavelengths on a more nearly constant
amplitude basis. This limits the ampli-
tude of the cut at the lower frequencies.
The frequency at which the change-
over is made is usually referred to as
the crossover point. In cheaper re-
corders, this presents no problem, but
in the higher-quality feedback-type re-
corders, this has to be done by appro-
priate recording equalization. With the
best type of feedback cutters, good
records may be recorded out to 12-15
kc, whereas on the cheaper types 5 or
6 kc is a desirable upper limit. When
a constant velocity record is reproduced
with a variable reluctance type of re-
producer, a constant voltage results.
For those parts of the spectrum cut at
constant amplitude, reproducing equali-
zation complementary to that used in
recording must be used.

Like all recording media, disk re-
cording is subject to its own peculiar
types of distortion. One of the most
common forms of disk distortion is
brought about by the fact that a sinus-
oidal wave cut into the record must
be tracked in reproduction by a stylus
of finite radius of curvature. It is ob-
vious that at short wavelengths it is
impossible under such conditions to
reproduce a true sinusoidal response.
Instead, a series of poids result which,
in the case of the more common lateral
type of disk recording, produce odd-
order harmonic distortions. Since the
wavelength for any given frequency
diminishes as the groove diameter of
the disk is reduced, such distortion
increases rapidly with diminishing
diameter for any given impressed fre-
quency. This has been studied in
detail by Pierce and Hunt and they show,
for example, that in 33^-rpm records,
distortion at 5000 cycles may amount
to as much as 30% for an 8-in. diameter,
dropping to as low as 2% for a 16-in.
diameter. Similarly for 78-rpm records
for the same frequency, distortion may
amount to 20% for a 4-in. diameter
and drop to approximately 1% for a

12-in. diameter. It is this factor which
limits the effective inner diameter on
33^-rpm microgroove records to 5 in.
and on 45 rpm to 3f in. Accompany-
ing this increasing distortion as the
groove diameter is reduced is a corre-
sponding loss in high-frequency response.
This may be corrected to a certain
degree by introducing variable equaliza-
tion in recording, increasing the high-
frequency input to the cutter as the
groove diameter is reduced. While
this may correct for high-frequency re-
sponse, it only adds to the distortion
resulting at the higher inputs.

Another form of distortion in re-
producing from disk records is known as
tracking distortion. This is brought
about by the fact that since the re-
producer is supported by a pivoted arm,
the angle which the axis of the stylus
makes with the groove is constantly
changing as the reproducer moves
across the record. This form of dis-
tortion is very complicated and results
in the generation of both even and odd
harmonics. This tracking error can
be reduced to a minimum by proper
design of the reproducing arm.

The commonly used expression "wow"
to denote low-frequency speed varia-
tions in sound reproduction had its
origin in the once-per-revolution speed
variation (wow) of cheap disk turn-
tables. At 78 rpm this corresponds to
a frequency of 1.3 cycles/sec, a rate
at which the ear is extraordinarily
sensitive to pitch changes. This low-
frequency rate is a difficult one to
correct in a mechanical system without
resort to very expensive and accurate
drive systems which are completely
beyond the range of the home pocket-
book. The problem is further aggra-
vated by the provision for three speeds
in many turntables, each of which may
call for somewhat different corrective
mechanical filtering. In the profes-
sional field, the problem of wow has been
largely overcome and flutter less than
0.1% may be attained.

314

October 1952 Journal of the SMPTE Vol. 59

Another factor which has limited
high fidelity in disk reproduction has
been the so-called needle scratch. This
has been accented by the use of the older-
type shellac records carrying an abrasive
for grinding the steel reproducer needle
to match the groove. This condition
has been greatly improved in recent
years by the adoption of improved pres-
sing materials such as acetate or Vinylite
and the wide adoption of permanent-
type needles. For home use, a signal-
to-noise ratio of the order of 40 db is
probably adequate, but for professional
use this should be improved to at least
50 db. A further improvement in
signal-to-noise ratio is the recent adop-
tion of the so-called hot stylus technique
in recording. This method usually
results in an improved signal-to-noise
ratio especially at the inside area of the
disk. Simultaneously, it appears to
result in improved high-frequency re-
sponse.

When one considers the mechanical
nature of disk recording and reproduc-
tion and the fact that a plastic with its
cold flow and general instability has
to be employed, the resulting fidelity
in modern disk recording may be con-
sidered a triumph of research in indus-
trial design and manufacture. When
one further takes note of the various
processes which are followed in going
from an original acetate cut record
through the plating and stamping
processes, one is further impressed at
the really excellent job that can be done
in modern disk recording.

Photographic Recording

Under ideal conditions of recording,
processing and reproduction, modern
photographic recording offers a medium
of high-fidelity sound reproduction the
equal, if not superior, to that of any
other method. Two well-known
methods — variable-density and vari-
able-area — are in wide use in photo-
graphic recording. With accurate con-
trol of film processing, extremely high

fidelity records may be obtained for
both variable-density and variable-area
methods. In the professional 35mm
field, such controls are successfully used
with a resulting high-quality product.
In the lower-cost 16mm field, it is a
matter of regret that much improve-
ment is still awaited in this regard.
Over the years since photographic re-
cording was first introduced, there has
been a vast improvement in the type of
photographic emulsions suitable for
both density and area recordings. Re-
cording devices and light-modulating
systems have been brought to a point of
near perfection, and the general improve-
ment in the electronic art has contributed
to practically distortion-free film and
reproducing systems.

A method of reducing background
noise unique to photographic recording
is the universal use of bias or noise-
reduction recording in which the average
transparency of the sound track varies
with the envelope of the sound wave-
form. This results in a minimum of
film grain noise and photocell hiss for
the low-level passages and automatically
permits a rise in these unwanted noises
as the signal amplitude increases.

The most difficult problem to overcome
in photographic recording has been
the development of high-quality trans-
port of the film past the point of optical
translation. The earlier film recorders
were subject to much wow and flutter
with disturbing rates varying all the
way from 1 cycle/sec to 96 cycles/sec,
the latter corresponding to the sprocket-
hole frequency of 35mm film. As a
result of much research into the nature
of flutter, improved designs of pro-
fessional 35mm recorders and repro-
ducers have been introduced in recent
years which are remarkably free from
flutter. Today, a photographic re-
corder with a total flutter content
exceeding 0.1% would have difficulty
finding any market. In 16mm photo-
graphic recording, due to the slower
speed employed, it is more difficult to

John G. Frayne: Comparison of Recording Processes

315

secure equally good film movement.
This is only too obvious in the reproduc-
tion of many 1 6mm sound tracks heard
over television programs. As a conse-
quence, high-quality 16mm film re-
corders should call for more careful
design and construction than the more
professional 35mm types. The con-
trary, however, has usually been the
result, due to the poorer economic
status of 16mm. The same comment
holds even more true for 16mm re-
producers. Instead of the sturdy pro-
fessional-type 35mm theater reproducers,
the 16mm field has until quite recently
been content to use lightweight, portable,
flimsily built 1 6mm reproducers to meet
a highly competitive market condition.
Recently, due to the wide use of 16mm
film in television, there have appeared
several professional 16mm reproducers
which tend to overcome this difficulty.

At the standard speed of 18 in. /sec
for 35mm, the practical upper limit to
frequency response is around 8-10 kc.
This limit is the result of recording and
printing high-frequency losses as well
as the losses introduced by the use of a
finite scanning slit in reproduction.
This has been recognized by the motion
picture industry in limiting frequency
response of theater systems to approxi-
mately 8 kc. In the 16mm field where
the film speed is only 40% that of 35mm,
it is much more difficult to secure a
wide frequency response. It is only by
resort to considerable equalization in
recording and reproducing that satis-
factory response to 6 kc may be made.
This inevitable shortcoming of 16mm
recording results in the well-recognized
"chesty" nature of the sound.

The limiting factor in the signal-to-
noise ratio in film recording is the
background noise produced by the
graininess of the photographic image
and also by the accumulated dirt and
scratches on the film. This usually
limits photographic tracks to a usable
signal-to-noise ratio of around 40 db,
although new tracks employing fine-

grain films and noise-reduction tech-
niques may give a value of at least 50 db.
Even though an excellent photo-
graphic track may be obtained from the
film processing laboratory, the final
result may be considerably affected by
the reproducing mechanism. Flutter
in the reproducer will produce results
equally as disastrous as those from poorly
made film recorders. Considerable dis-
tortion, especially in the variable-area
system, may be encountered by non-
uniformity of the scanning beam in the
reproducer and even more seriously by
failure to have the reproducing scanning
beam in the correct azimuth. Other
limitations in reproducing, especially
in 16mm, are low-cost amplifier systems
which do not have sufficient output
capacity for the higher-level passages
on the film and insufficient hum filtering
which in many cases permits an audible
60-cycle reproduction from the loud-
speaker. In the matter of loudspeakers,
the photographic system probably fares
better than either of the other two
methods. There has been a vast im-
provement in loudspeakers in profes-
sional 35mm theaters. This cannot be
said, however, for the speakers used in
the lower-cost portable 16mm repro-
ducing systems.

Magnetic Recording

In common with the other recording
techniques discussed above, magnetic
recording is also affected by uneven
motion of the magnetic tape or film in
the recorder and reproducer. The ex-
treme flexibility of the standard J-in.
tape aids considerably in simplifying
the tape-pulling mechanism and it is
possible to obtain considerable freedom
from very low flutter rates with a rela-
tively inexpensive drive. The common
capstan-type drive usually introduces
low-frequency flutter rates which, how-
ever, are considerably higher than those
encountered in disk recording and are,
therefore, not so objectionable to the
ear. Magnetic recording, however, does

316

October 1952 Journal of the SMPTE Vol. 59

introduce a considerable amount of
high-frequency flutter of a somewhat
random nature which may be traced to
the irregular motion of the tape or film
over the magnetic head. Fortunately,
these rates are sufficiently high so that
their effect on the ear is negligible
except at the higher audiofrequencies
such as some of the higher overtones
from string instruments. This irregular
motion of the tape over the magnetic
head also introduces considerable ampli-
tude distortion which produces an effect
almost indistinguishable from that of
the high-frequency flutter. Thus, at
the commonly accepted speed of 15
in. /sec, both of the effects produce a
very harsh quality if the sound spectrum
is pushed up to the 1 5-kc limit.

Magnetic tape recording utilizing the
high-frequency bias may be reproduced
with a minimum of distortion which is
generally lower than that in either disk
or photographic recording. At the same
time, a signal-to-noise ratio of 50 to
60 db may be obtained. This, however,
calls in recording for a very high-
quality, high-frequency bias oscillator
with a second harmonic content about
60 db lower than the fundamental.
The ratio of the high-frequency current
to the maximum audio current must be
of the order of 10 to 20. To achieve
the low noise level and relative freedom
from distortion, extreme care must be
taken to insure that the magnetic head
and associated shield do not acquire
any permanent magnetism, as the d-c
magnetic field thus produced acts in a
manner directly analogous to the pres-
ence of second-order harmonic com-
ponents in the high-frequency bias
oscillator. One common result of these
d-c fields is a pronounced rumble in
reproduction. This same effect may
also be traced to improperly erased
tape. With the proper value of high-
frequency bias for any given magnetic
head and tape, the distortion above the
so-called overload of the medium is
mostly third-order harmonic compo-

nents, the second-order being almost
entirely absent. Experience has shown
that considerable overload may be
tolerated and this is generally attributed
to the absence of the more unpleasant
even-order harmonic components. A
disturbing factor in J-in. tape is the
presence of so-called "print-through"
from layer to layer, resulting in what
appears to the listener as an echo.
This can be prevented by reducing peak
amplitudes in the recording and may
be prevented from becoming too serious
by avoiding storage of recorded tape in
excessive high -temperature locations or
in the proximity of high magnetic or
electrostatic fields.

The frequency response from magnetic
film recorded at constant current input
to the recording head increases at a 6 db
per octave rate over a considerable
portion of the audio spectrum. It then
flattens off and begins a fairly sharp
decline. This dropping off at the
upper frequencies results from two
causes — one, demagnetization in re-
cording at the shorter wavelengths;
and two, the scanning losses which are
directly analogous to those found in film
reproduction. For a 0.5-mil reproduc-
ing gap and speed of 15 in./sec, this fall-
off in high-frequency response begins
in the neighborhood of 2000 to 3000
cycles. It is customary to correct for
the 6 db per octave slope by inserting
a simple RC correcting network in the
reproducing circuit, and a fairly flat
response may be obtained down to
approximately 100 cycles by this simple
expedient. Below this point, irregu-
larities in low-frequency response are
frequently encountered, and more com-
plicated means of equalization must be
employed if these are to be smoothed
out. To insure a wider, higher fre-
quency response, equalization must be
used and it is customary to do this
partly in recording and partly in re-
producing. As pointed out above, a
tape speed of 1 5 in./sec in response may

John G. Frayne: Comparison of Recording Processes

317

be made fiat out to approximately 1 5 kc
without resort to excessive equalization.
One of the problems peculiar to
magnetic recording is the care that
must be taken to avoid excessive 60-
cycle hum pickup in the reproducer.
Since the common power-line frequency
of 60 cycles may have a gain 20 to 30
db higher than say 1000 cycles in order
to correct for the nonlinear frequency
response referred to above, the pickup
head and the input circuit, especially the
input transformer of the preamplifier,
must be well shielded to avoid pickup
from ambient 60-cycle fields. For-
tunately, the well-known ear charac-
teristic for medium sound reproducing
levels aids in reducing the effect of such
a disturbing frequency. The ear's being
at least 20 db less sensitive at this fre-

quency than at a 1000-cycle tone means
that an effective signal-to-noise ratio
of 40 db at 60 cycles will be equivalent
to a 60-db signal-to-noise ratio at the
higher frequency.

In conclusion, we may note that all
three media have their own particular
factors that limit their fidelity. When
all factors including economic are taken
into consideration, the magnetic medium
appears to offer the greatest possibility
of high-quality sound reproduction with
a minimum investment in recording and
reproducing equipment. The re-use ol
the tape and the general simplicity of
operation are other factors which seem
to be responsible for the remarkably
wide use of the magnetic medium in the
very short period since its general intro-
duction in this country.

318

October 1952 Journal of the SMPTE Vol. 59

A Building-Block Approach to
Magnetic Recording Equipment Design

By KURT SINGER and J. L. PETTUS

The requirements of magnetic recording equipment for sound motion pictures
have been found to vary greatly with different customers. In order to pro-
vide the necessary flexibility to meet these different requirements and to
include various custom features, the functional units of a magnetic recording
channel have been designed on separate rack-mounted panels which can be
installed in varying arrangements in a standard amplifier rack. These include
items for both single-track and three-track equipments, and film widths of
16mm, 17. /mm and 35mm.

HE EQUIPMENT required for a sound
recording plant varies widely depending
on the type of recording, the size of the
associated studio, and the magnitude of
the plant operation. In this respect
magnetic recording or reproducing
equipment differs in considerable detail
over its predecessor, photographic re-
cording and reproducing equipment.

i In the latter case, certain facilities were
necessarily reserved for photographic

f film handling. These included dark
rooms, film magazines and lighttight en-
closures in the recording facilities. In
contrast, magnetic equipment offers some
consolidation in plant layout as well as
certain conveniences in operation.

Presented on October 18, 1951, at the
Society's Convention at Hollywood, Calif.,
by Kurt Singer and J. L. Pettus, Radio
Corporation of America, RCA Victor Div.,
Engineering Products Dept., 1560 N. Vine
St., Hollywood 28, Calif.

The requirements of magnetic record-
ing/reproducing equipment for sound
motion pictures have been found to vary
greatly with different installations.
These requirements plus the fact that
many studios will wish to install mini-
mum equipment at the beginning and
"grow" with the development of mag-
netic recording, led the authors to the
conclusion that studio equipment should
be made of carefully planned units so
coordinated that they could be easily
fitted together to provide almost any de-
sired combination of equipment layout.
This is essentially the "building block"
idea which is today employed in many
types of industrial apparatus. Thus,
when expanding a system such as from a
few magnetic recording channels to a
more comprehensive system or from a
single-track to a triple-track recorder/-
reproducer, it is not necessary to add
entirely new recorder mechanisms but
rather to increase the number of compo-

October 1952 Journal of the SMPTE Vol. 59

319

320

October 1952 Journal of the SMPTE Vol. 59

nents as desired. Moreover, this is
readily possible if all of the component
assemblies have been designed to mount
on a standard relay cabinet rack or
equivalent having the industry standard
multiple dimensioning. The three sys-
tem layouts described in the following
text have been chosen to illustrate the
wide range of equipment combinations
which are practical. For the most part,
these are actually in use or are now being
installed in several large motion picture
studios.

Of the different equipment combi-
nations to be described, types A and B
utilize a single magnetic track while type
C provides three sound tracks having all
tracks recorded and/or reproduced
simultaneously and positioned in accord-
ance with Motion Picture Research
Council proposed standards.1

Basic Mechanical Arrangement

There are several ways of arranging
components in the vertical plane but
these generally follow the rules of hand
and eye levels for those items requiring
the greatest amount of operation atten-
tion. An example of a single-track mag-
netic recorder/reproducer channel is
shown in Fig. 1 and identified as RCA
type PM-66 equipment. Here the ex-
treme upper portion of the rack supports
the bias oscillator/preamplifier followed
by a film-feed assembly, a control panel, a
1 film-drive mechanism, a film take-up
assembly after which are located power
supplies and other miscellaneous audio
components. Figure 2 shows a number
of these units assembled in line for a
multiple-channel installation, yet with
each unit being capable of independent
operation.

Figure 3 shows a type B arrangement
for application where it is desirable to
reduce the vertical height of the mechani-
cal components to a minimum. Here
the controls have been relocated on the
film-feed assembly to conserve space.
As in the type A equipment, the audio

components are located above and below
the mechanical units and positioned as
to their operating convenience.

Type C equipment is shown in Fig. 4
as an arrangement which provides a
three-track magnetic recorder/repro-
ducer channel and is identified as RCA
type PM-63 equipment. Here it was
necessary to assemble all audio compo-
nents in two racks and all mechanical
components in a third rack. All racks
are tied together to form a single and
complete unit assembly. Such an ar-
rangement provides for maximum serv-
iceability to all elements but occupies
bnly minimum plant space. Here again
many components as shown in Fig. 1 are
used with only minor alteration to the
film-drive mechanism for the number of
magnetic-head assemblies employed.

Selection of component assemblies in
practice follows the requirements and
specifications for a given installation.
To begin with, the width of the recording
medium, the number of magnetic tracks
per channel and the required film ca-
pacity determine the basic elements. In
general, the width of the film does not
alter the basic design except for the
physical size of certain parts and the
speed of the film-driving mechanism.
This latter difference has been chiefly
limited to the use of 1 6mm film operating
at 36 fpm and 17-| or 35mm film operat-
ing at 90 fpm. However, in view of fur-
ther economy in magnetic recording, the
use of 17^mm film operating at 45 fpm
for all original or production recording,
is gaining favor in the industry. Mag-
netic recording equipment for 45 fpm
operation was presented before this So-
ciety in a paper entitled "A Technical
Solution to Magnetic Recording Cost
Reduction."2

The number of magnetic tracks regard-
less of the width of the film has been pri-
marily limited to the use of a single track
on all widths for production recording
and triple tracks on 35mm film in dub-

Singer and Pettus: Magnetic Recording Equipment

321

Fig. 4. Triple-track rack assembly, Type C equipment.

bing or re-recording operations. Of
course, there are many possibilities of
using a plurality of tracks on either of the
other two film widths.

Description of Mechanical Components

A. Film Feed and Take-up Assemblies. A
panel of approximately 1 5f in. high will
accommodate a film capacity of 2000 ft.
This size was chosen as being most satis-
factory in the majority of installations.
In the past, many recorder /reproducer
designs have used a rather simple friction-
type clutch as an integral part of the feed
and take-up assemblies to tension or wind
the film on the respective film reels. The
applied tension between start and finish
pay-out or take-up of a 2000-ft-roll of
35mm film wound on a 2-in. diameter
core, was found to vary by a ratio of 1 : 8
under average operating conditions.

Such a variation reflects an undesirable
condition to the film-drive mechanism.
Furthermore, the desire to incorporate
rewinding from reel to reel as a feature on
new equipment is well founded.

These two factors guided the design to
make use of a torque-type motor to serve
as a tensioning device having a nearly
linear characteristic for both holdback
and take-up as well as being suitable for
a high-speed rewind. The first function
was obtained by applying varying poten-
tial to the motor in proportion to the
amount of film on the reel and phased for
rotation opposite that of the film pay-out.
This provided an ideal holdback system.
Similarly, it also provides an ideal
take-up system except that rotation of
the torque motor must agree with the
direction of film winding and have some-
what greater torque. The third function

322

October 1952 Journal of the SMPTE Vol. 59

R-l

MASTER SWITCH REVERSE

Fig. 5. Schematic of torque motor voltage controller.

as a rewind was obtained by using the
motor at its rated output as a propulsion
device. The electrical elements of this
assembly are shown schematically in Fig.
5. From this, it will be noted that the
use of a variable series resistance (R-l) in
one leg of a single-phase motor, serves to
vary the motor torque for either hold-
back tension or forward torque for
take-up. The resistor (R-l) is varied by
a commutator (S-l) by means of a fol-
lower arm in contact with the periphery
of the film roll. Additionally, a relay
(K-l) is used to vary the overall torque
curve when the motor is functioning for a
take-up instead of a holdback as in the
case of reverse operation. This relay is
normal in the holdback function and
energized by the master control switch
for the reverse or take-up function. As
shown in Fig. 5, the commutator switch
(S-l) is in its initial position at the maxi-
mum film roll diameter thus placing the
least amount of R-l in series with a sec-

ond resistor (R-2) and this combination
being seen by one leg of the torque motor.
As the commutator switch progresses
with a decrease in film roll diameter, sec-
tions of R-l are automatically added,
proportionally reducing the motor
torque. As the last two steps are
reached, R-l is opened allowing only the
inherent load of the motor-drive assem-
bly to serve as friction in the holdback
function, these two steps being at diam-
eters less than 5 in. When functioning as
a take-up device, relay K-l becomes
energized and shorts out R-2 to increase
the overall torque range. Additionally,
steps 1 and 2 of S-l are seen by R-l, thus
giving a potential to the motor at the
minimum or starting diameter of the
take-up roll. Controlling the torque of
each motor by the described method pro-
duced a film tension characteristic con-
stant within 2 oz throughout the length
of a 2000-ft reel using a 2-in. OD core.

Singer and Pettus: Magnetic Recording Equipment

323

Fig. 6. Film-drive mechanism.

As an operating convenience, the fol-
lower arm is automatically retracted from
the film reel by means of a solenoid ener-
gized through the master control switch
when positioned at OFF. Upon setting
the master switch for the desired oper-
ation of the film drive, the follower arm is
released and allowed to seek the periph-
ery of the film roll. Thus, a predeter-
mined potential to the torque motor is
automatically established.

B. Control Panel Assembly. As shown in
Fig. 1, controls for the film-drive mech-
anism, as well as for rewinding, are
mounted on a separate panel. An ex-
ception to this arrangement was shown
in Fig. 3 where these controls were placed
on the film-feed assembly in order to con-
serve rack space for a particular in-
stallation. In general, the separate
panel allows the use of larger film reels
and gives several operating as well as
manufacturing conveniences. In the
latter respect, the associated film-drive
mechanism may use any of the industry
standard motors including the combi-
nation synchronous/interlock type. The

use of a separate control panel therefore
permits a variety of electrical combi-
nations to suit the associated motor sys-
tems without alteration of the other elec-
trical circuits. Figure 1 shows the
master switch designated for operation of
a combination synchronous/interlock
film-drive mechanism motor. This
switch is divided into eight positions in
order to give independent switching for
the respective sections of the motor. It
is also seen that on either side of the OFF
position for synchronous motor control,
there appears a READY position which
permits energizing the feed and take-up
motors before completing the circuit to
the film-drive mechanism motor. Thus,
the torque motors, being pre-energized
ahead of the actual rolling of the overall
mechanism, remove all slack in the film
path and permit the feed and take-up
reels to follow the acceleration or de-
celeration of the film-drive mechanism
motor. READY positions for interlock
operation are not required since the
torque motors are energized on the
LOCKING cycle of the interlock motor
system.

324

October 1952 Journal of the SMPTE Vol. 59

DRUM

ROLLER

SPROCKET

ROLLER i

OIL DASH POT

DRUM

Fig. 7. Schematic of film-drive mechanism mechanical filter assembly.

A key switch, which controls the re-
spective torque motors through relays,
allows film to be rewound from reel to
reel with the direction established by the
position of the key. For instance, if re-
winding is to be from the lower to the
upper reel, positioning the rewind key
switch in the UP position connects the
upper motor for maximum torque and
likewise connects the lower motor for re-
duced and reversed torque in order to
establish tension in the film. Rewinding
in the reverse position follows a similar
procedure.

C. Film-Drive Mechanism. This assem-
bly might well be considered a basic item
in the building-block plan for a magnetic
recorder and/or reproducer unit. The
foregoing discussion is therefore primarily
concerned with the accessory items re-
quired by the film-drive mechanism but
varied to suit a particular installation.
Figure 6 shows the components of the
drive unit. The base of this assembly
consists of a cast aluminum alloy plate

occupying 1 0^ in. of vertical rack space.
Attached to this plate are a drive motor, a
mechanical filter system, magnetic
heads — either single- or triple-type — a
footage counter and several film-guide
rollers, etc. The drive motor is worthy
of mention to the extent that an integral
part of it is a reduction-gear unit whose
output shaft is suitable for direct coupling
to the film-drive sprocket. The speed re-
duction from motor to sprocket is ob-
tained by single-series helical gearing.
Ratios varying between 10 '1 and 125^9
to suit the many permissible different
types of motors and film speeds are used.
Since the drive motor does not power the
take-up system, its frame size has been
reduced to a minimum while maintain-
ing a power output in the order of 3;1
over that of the actual torque require-
ment. This motor unit develops ap-
proximately 20 mechanical watts when
designed as a three-phase motor and
somewhat more when designed as an
interlock-type motor. The use of per-
manently lubricated bearings together

Singer and Pettus: Magnetic Recording Equipment

325

Fig. 8A. Single-track magnetic-head
assembly.

with a grease-filled gearbox reduces
maintenance and operating attention to a
minimum.

The mechanical filter system, sche-
matically shown in Fig. 7, consists of two
drum-shaft assemblies having identical
flywheels as inertia elements. Both
drums are film-pulled. Two sprung
tensioning rollers with damping applied
to one tension roller comprise the other
elements of the filter system, the damping
being obtained by means of a fluid sili-
cone oil type dashpot connected to one
roller arm by a mechanical linkage.
The entire system is near critically
damped with a resonant frequency of ap-
proximately H cycles/sec.

Magnetic head assemblies may be, as
previously mentioned, selected to suit
the particular requirements of the in-
stallation, i.e., single- or triple-type
tracks. Either assembly is interchange-
able with respect to the film-drive unit.
The single-track type is shown in Fig.
8A. Here it is seen that the head is
mounted by means of a one-piece holder
having a ball-and-socket type of anchor-
age which allows longitudinal, lateral and
transverse adjustments of the head with
respect to the recording medium.3 The
use of a shoe which contacts the film on
the edge opposite the sound track, and
which is of a width equal to the magnetic
track, has been found advantageous.
This shoe maintains the plane of the film
across the magnetic head as well as dis-

Fig. 8B. Triple-track magnetic-head
assembly.

tributing the unit area pressure to mini-
mize head wear. An interesting note is
that the use of a hardened stainless steel
shoe was found most practical for obtain-
ing a wear characteristic nearly equal to
that of the mu-metal used in the mag-
netic-head, laminated pole pieces.

Also seen in Fig. 8B, the triple-track
assembly employs three heads arranged
in line and positioned in accordance with
the Motion Picture Research Council's
proposed standards for sound-track posi-
tions.1 This assembly, while obviously
more complex than that of the single-
track magnetic-head unit, provides the
same individual head adjustments al-
though accomplished in a somewhat dif-
ferent manner. The lateral or azimuth
adjustment of each head is obtained by
pivoting the head-mounting yoke on a
supporting arm. The transverse adjust-
ment is obtained by pivoting the indivi-
dual arms on a lateral supporting shaft,
and the longitudinal adjustment is ob-
tained by moving the entire head assem-
bly with respect to the mounting base.3
No supporting shoe is required by the
triple-track assembly since the heads
themselves contact the film uniformly
across its width. The construction of the
magnetic head proper, used in both
single- and triple-track units, follows that
described by Rettinger.4

When the film-drive mechanism is to
serve as a recorder with monitoring, two
identical head assemblies are employed,

326

October 1952 Journal of the SMPTE Vol. 59

each assembly being positioned near the
respective drum-shaft assemblies. These
positions were chosen after extensive in-
vestigation for optimum performance in
both constancy of motion and uniform
output from the recording medium. A
more comprehensive discussion of this
investigation was presented before the
Society in a paper entitled "Twin-Drum
Film-Drive Filter System for Magnetic
Recorder-Reproducer. ' ' 5

Among other features of the film-drive
mechanism believed to be of interest, is
one commonly called the free-wheeling
sprocket. Specifically it is a means of
disengaging the film sprocket from its
drive source and is considered essential
to any reproducer using an interlock mo-
tor system. With this facility, synchro-
nization marks may be readily brought
to a reference position without disturbing
the interlock of the driving motor. Such
an assembly is shown in Fig. 9 in an ex-
panded view. Essentially, this consists
of a multi-jaw coupling which may be
manually disengaged to free the film
sprocket. It will be seen that one-half of
the multi-jaw coupling is fixed to the
sprocket drive shaft and following this is
a spinner knob which contains the mating
half of the multi-jaw coupling, free to ro-
tate on the shaft. On the rear side of
the spinner knob is a driving pin which
accurately engages at all times with a
hole in the film sprocket proper and
therefore serves to drive the latter.
Between the spinner knob and the
sprocket lies a compression spring which
normally forces the spinner knob toward
the fixed half of the multi-jaw coupling.
By exerting an inward force on the spin-
ner knob, the coupling becomes dis-
engaged and the film sprocket is then
"free-wheeled." Following the sprocket
is a collar which is likewise driven by a
pin engaging the film sprocket and ro-
tates at all times with the sprocket. On
the rear face of this collar is a ladder-
chain sprocket which drives the footage
counter in synchronism. Behind this is
a smaller collar — fixed to the drive shaft

Fig. 9. Free-wheeling sprocket and drive-
motor assembly.

— which forms an axial stop for the
entire assembly when the foregoing items
are assembled in their true position on
the drive shaft. Since the film sprocket
contains 32 teeth in the case of 35mm
applications, a multi-jaw coupling also
having 32 teeth was chosen. It follows
therefore that synchronism is maintained
within one sprocket pitch for 35mm film
and to an even closer degree for 16mm
film where the sprocket contains 20
teeth. This arrangement will advance
or retract film through the driving mech-
anism at the rate of approximately 6 in.
per revolution of the spinner knob.

D. Accessory Equipment. In the build-
ing-block plan, a number of accessories
have been developed to provide addi-
tional conveniences in operation as well
as a means of reducing production costs.
These include: (a) magnetic erasing fa-
cilities while recording either single or
triple tracks; (b) a predetermining re-
wind footage counter; and (c) photo-
graphic-type sound reproducers for both
16mm and 35mm films. The erasing
unit employs two erase heads in cascade
for each sound track, making a total of
six heads in the unit. The geometry of
the film path between feed reel and film-
drive mechanism is slightly modified to
bring the erase unit into use. This con-
sists of threading the film about a series of

Singer and Pettus: Magnetic Recording Equipment

327

Fig. 10. Predetermining counter assembly.

Fig. 11. 35mm photographic reproducer assembly.

328

Fig. 12. Oscillator-preamplifier.
October 1952 Journal of the SMPTE Vol. 59

fixed rollers which allow the film to con-
tact the erase heads. When erasing is
not wanted, the film is threaded directly
past the erasing unit. Thus, the differ-
ence in film threading, plus an enclosure
around the erasing heads, reduces the
accidental use of the erasing facilities to a
minimum. Each erase head dissipates
1.6 w, making a total of 3.2 w per track
of erase current power. The frequency
is nominally 68 kc and derived from the
recording bias oscillator. This amount
of erase power provides a 70-db erasure
below 100% modulation or results equiva-
lent to that obtained by the conven-
tional 60-cycle bulk eraser.

The predetermining footage counter
accessory is shown in Fig. 10. It is used
in rewinding to a given point without
operator attention. A specific use for
this convenience is, for example, in scor-
ing music, where playbacks and transfers
are involved. This assembly consists of
a special counter which is film-driven and
several additional relays in the electrical
circuit for controlling the film feed and
take-up torque motors. In operation,
the counter is set to a given number of
feet to be rewound and the rewind con-
trol switch positioned in the desired di-
rection of rewinding. As the film travels
from reel to reel, the counter subtracts
toward zero. At 10 ft from zero the
counter anticipates and trips an electrical
control which applies a braking voltage
to the respective torque motors. This
braking action is maintained by a time-
delay relay circuit during the deceler-
ation period, and when the counter
reaches zero both the braking action as
well as the power are released. At this
point, the torque motors are automati-
cally restored to their normal functions
of feed and take-up. The footage coun-
ter is driven by wrapping the film about
a large rubber-tired roller, with the de-
gree of wrap being maintained by two
smaller rollers of the conventional type.
When the predetermining counter oper-
ation is not wanted, the film path for re-
winding is threaded to by-pass the coun-

ter drive. The electrical control ele-
ments have been designed to stop film
travel within two to three feet of a given
point, this point being in the direction of
over-travel. The starting point is then
brought into view during rethreading of
the film-drive mechanism, since the oper-
ator's natural tendency is to pull this
amount of slack film from the feed reel for
the threading operation. Exact syn-
chronism is then obtained by turning the
free-wheeling sprocket.

The third accessory item is a photo-
graphic sound reproducer unit for both
1 6mm and 35mm applications. The latter,
shown in Fig. 11, is suitable for 100-
mil standard, 100-mil push-pull and 200-
mil push-pull sound tracks. It is be-
lieved that most sound-recording plants
find it necessary to handle photographic
records at different times regardless of
the extent of their magnetic plant fa-
cilities. Since many of the components
of a magnetic reproducing channel might
well be common to a photographic repro-
ducing channel, it is logical that a dual-
purpose reproducer will reduce the over-
all plant investment. Again the build-
ing-block plan permits the use of another
unit in conjunction with those items con-
sidered common to either type of repro-
ducer. The photographic sound repro-
ducer need have only the necessary opti-
cal-scanning facilities and a means of
directing the film for scanning. This has
been accomplished by mounting the
necessary optical elements on a panel 8|-
in. high and assembling in the standard
relay rack directly below the magnetic
film-drive mechanism. The photo-
graphic reproducer contains its own
mechanical filter system but its driving
power is derived from a synchronous rub-
ber-belt drive from the magnetic film-
drive unit. In operation, the film is
threaded to by-pass the magnetic unit.
Likewise, the photographic unit is by-
passed when using the magnetic unit.
Preamplifiers for both the 16mm and
35mm reproducers are mounted directly
behind the respective mechanisms and

Singer and Pettus: Magnetic Recording Equipment

329

Fig. 13. Erase amplifier (front view).

330

Fig. 14. Erase amplifier (service position).
October 1952 Journal of the SMPTE Vol. 59

provide an output level of approximately
— 2 dbm and — 12 dbm, respectively.

A variety of amplifiers and bias oscil-
lators are available to complement the
above-mentioned alternative equipment
arrangements. For single-track record-
ing and reproducing, the amplifier-
oscillator known as MI-10248 or MI-
10248-A, shown in Fig. 12, is provided.
This unit contains a combining network,
bias oscillator and bias meter. In addi-
tion, it also provides for a separate self-
contained playback amplifier capable of
amplifying the signal from the monitor
head to a level of +4 dbm. Output im-
pedances of 10, 250 and 600 ohms are
available so as to provide for headset
monitor or for transmission to the re-
recording channel. Suitable switching
facilities deactivate the oscillator during
playback or in the OFF position. The
oscillator also contains a high-frequency
boost equalizer which is used to shape the
recording characteristic to obtain flat
output to 8000 cycles. A separate wind-
ing on the oscillator coil permits connec-
tion to an MI-10263 Erase Amplifier as
shown in Figs. 13 and 14. By means of
this amplifier, it is possible to raise the
output voltage from the oscillator to a
level sufficient for erasing. This erase
amplifier contains its own a-c power sup-
ply and is capable of delivering 50 w at
68 kc at a distortion of less than 0.5%.
At normal erase power requirements, the
wave-form distortion from this amplifier
is on the order of 0.1% or less.

For triple-track recording or repro-
ducing, a three-channel bias oscillator is
provided. This oscillator, known as the
MI-10228-A, is usually mounted to-
gether with the MI-10262-A Switching
Panel on a common frame and is shown
in Figs. 15 and 16. A master oscillator
operating at a nominal frequency of 68
kc supplies three independent push-pull
amplifiers which in turn furnish bias cur-
rent to the three recording heads. The
switching panel permits the combining of
the bias currents with the signal before it
reaches the heads and also provides

switching means for turning the MI-
10228-A oscillator on and off. Three
separate bias meters are contained on the
switching panel to permit independent
metering of the three recording heads.
For playback, there are available plug-in
amplifiers (Fig. 17) which may be con-
nected singly or in cascade so as to obtain
almost any desired output level from the
reproducing heads with frequency char-
acteristics flat up to 8000 cycles. Six
such playback amplifiers are housed on a
common shelf. These six amplifiers fur-
nish the playback amplification for a
triple-track reproducing setup. For re-
. cording amplifiers, plug-in amplifiers, in
external appearance very similar to the
playback amplifiers, are available.
However, any power amplifier capable
of providing a level of +22 dbm at an
output impedance of 600 ohms, may be
used. In order to obtain the optimum
signal-to-noise ratio, we have standard-
ized on the use of a low-frequency pre-
equalizer during recording. This unit,
shown in Fig. 18, raises the 60-cycle re-
gion of the recording characteristic by 6
db and consequently permits the use of 6
db less post-equalization during repro-
ducing. This expedient reflects in a
gain in signal-to-noise ratio, since hum
frequencies, such as 60 cycles, now re-
quire 6 db less playback amplification.
The insertion loss of this constant resist-
ance equalizer is 10 db. It may be con-
nected before or after the power amplifier
dependent on the power-handling capac-
ity of this amplifier. The performance
of these magnetic channels is best ex-
pressed by stating that the overall fre-
quency response is flat within 1 db from
40 to 8000 cycles at film speeds of 90 or
45 fpm, and flat within 1 db from 50 to
7000 cycles at film speed of 36 fpm. The
signal-to-noise ratio is consistently 60 db
or better, referred to 100% modulated
track. In order to obtain this perform-
ance, all heaters are operated from d-c
supplies which have a ripple content of
6 mv or less. The ripple content of the
B supplies is 1 mv or less. The flutter

Singer and Pettus: Magnetic Recording Equipment

331

Fig. 15. Triple-track oscillator and switching panel

Fig. 16. Triple-track oscillator and switching panel (cover removed).

332

October 1952 Journal of the SMPTE Vol. 59

Fig. 17. Magnetic playback amplifier.

Fig. 18. Recording equalizer.

content of a recording reproduced on
either single- or triple-track equipments is
less than 0.1% rms total with less than
0.05% rms being 96 cycles flutter.5 Re-
winding speed is approximately 900 fpm.
Starting time is in the order of 4 sec for
35mm or 17^mm equipment at 90 fpm,
and approximately 5 sec for 1 6mm equip-
ment at 36 fpm.

In order to complement the photo-
graphic-film reproducing facilities the
following amplifiers are available:

Fig. 19. 16mm photocell amplifier.

1. For 16mm reproducing, the MI-
10239-A, shown in Fig. 19, can be sup-
plied. This is a two-stage negative feed-
back amplifier capable of furnishing
photocell polarizing potential and of
amplifying the output from a photocell to
a level of —10 dbm.

2. For the reproducing of 35mm opti-
cal track there is available an amplifier of
the plug-in broadcast type known as
MI-10271 which in appearance is similar
to magnetic playback amplifiers. This

Singer and Pettus: Magnetic Recording Equipment

333

amplifier also furnishes photocell polariz-
ing potential and is customarily used
with a balancing network which forms
part of the MI-29135 optical system.

References

1. Motion Picture Research Council Rec-
ommendation 58. 301 -B.

2. Kurt Singer and H. Gonnell Ward, "A
technical solution of magnetic recording
cost reduction," Jour. SMPTE, 58: 329-
340, Apr. 1952.

3. Terms are those defined by N. M.
Haynes, "Magnetic tape and head align-

ment nomenclature," Audio Eng., 33:
22, June 1949.

4. M. Rettinger, "A magnetic record-
reproduce head," Jour. SMPTE, 55:
377-390, Oct. 1950.

5. Carl E. Hittle, "Twin-drum film-drive
filter system for magnetic recorder-
reproducer," Jour. SMPTE, 58: 323-
328, Apr. 1952.

6. Proposed American Standard, Z57.1 /68,
Method for Determining Flutter Con-
tent of Sound Recorders and Repro-
ducers, American Standards Assn., 70
E. 45 St., New York City.

334

October 1952 Journal of the SMPTE Vol. 59

A-C High- Intensity Arc Slide Projector

By ARTHUR J. HATCH

This paper describes a high-intensity arc slide projector which is powered
from a 110-v, 60-cycle convenience outlet and requires only 10-amp supply.
The resulting intensity of illumination is sufficient for screens of 35 ft in width.

modern slide projector, shown in
Fig. 1, using a high-intensity a-c carbon
arc as a light source, has been developed
to cover both the large-screen areas of
drive-in theaters and smaller screens
where an exceptionally high level of
illumination is desired.

With this high-intensity a-c arc
adapted for 3| in. by 4 in. slides, 7500
Im are projected, with no slide in the
carrier. Expressed a different way, this
7500 1m projected to a 35-ft wide screen
will produce a screen brightness of
approximately 9 ft-L, which incidentally
is the lower limit of the SMPTE screen
brightness range for 35mm projection.
For a 50-ft wide picture the screen
brightness will be nearly equal to that
usually obtained on the average 50-ft
drive-in screen with 35mm projection.

With small-size screens of 10 to 12 ft
in width, the brightness may approxi-
mate 70 ft-L, which is sufficient to obtain
a reasonably good contrast even with the
normal room lighting remaining on.

The complete projector comprises the
arc lamphouse, optical system, slide
carriers, and fan and transformer, all
assembled as a table unit 78 in. long
and weighing 175 Ib. The table is ad-
justable in height by means of its four

Presented on April 22, 1952, at the Society's
Convention at Chicago, 111., by Arthur
J. Hatch, The Strong Electric Corp.,
87 City Park Ave., Toledo 2, Ohio.

legs, from 36 in. to 56 in., and tillable
from 10° upward to 30° downward.

The reflector-type arc lamphouse and
power supply elements are essentially
the same units used in the "Trouper"
arc spotlight.* The lamphouse is com-
plete with carbon holders, motor-driven
carbon feed, reflector tilt adjustments,
arc focus knob and arc imager screen.

The trim of 6 mm by 7 in. copper-
coated high-intensity a-c carbons is
burned in coaxial alignment at 45 amp
and 21 v a-c. The burning time for a
single trim of carbons is 1 hr 20 min.

Although the first development with
this new a-c projector has been for
3j by 4 in. slides, simple adaptations
can be used to project both larger and
smaller material. However, in the case
of 2 in. by 2 in. material or smaller,
heat-removing means in the form of heat
filters or heat deflectors will have to be
used in the light beam to prevent
damage to the slide.

The optical system is arranged so
that the light from the arc is gathered
by a lOj-in. diameter elliptical reflector
which has a focus of 3 J in. and a working
distance of 24 in. This reflector con-
verges the beam of light through a
plano-convex lens and thence through
the slide aperture to the objective lens.

* R. Ayling "New portable high-intensity
arc spotlight," Jour. SMPE, 53: 408-416,
Oct. 1949.

October 1952 Journal of the SMPTE Vol.59

335

Fig. 1. A-C Arc Slide Projector.

The magnification of the carbon crater
on the slide aperture is sufficient to
cover a 2 in. by 2 in. slide. When
3j in. by 4 in. slides are projected, a
negative lens is placed in the beam of
light between the lamp and plano-
convex lens to increase the magnification
sufficiently to cover the larger aperture.
The power transformer which isolates
the a-c line potential from the lamp-
house draws 10 amp from any 115-v
convenience outlet and delivers 45 amp
at 21 v to the arc. The eight-point
rotary tap switch and indicating meter

provide a convenient means of coi
pensating for commercial variations
the a-c line voltage.

The indicating meter, in reality a volt-
meter with a suppressed zero, is con-
nected across a portion of the trans-
former primary winding. When the
hand of the indicating meter scales in
the green zone, the volts per turn of the
transformer primary are at the right
value to deliver the correct amount of
power to the arc. The tap switch is
simply turned until the primary volts

336

October 1952 Journal of the SMPTE Vol.59

per turn are correct as indicated by the
meter.

A fan of 50 cu ft/min capacity directs
a moving air stream across the slide to
prevent damage to the slide. This fan
is started when the arc power supply is
turned on. With the cooling from this
blower, it is possible to project dense
3j in. by 4 in. slides for periods of an
hour or more continuously without
visible deterioration to the slide.

The arc "on-off" switch is located at
the top rear of the lamphouse. A
manually operated dowser interposed
just before the slide carrier and lens
assembly enables the arc to be burned
in a stand-by condition.

Single-element objective lenses have
been found suitable for use with 3j in.
by 4 in. slides in the focal length range

of 17 in. to 30 in. Corrected objective
systems are generally necessary for focal
lengths shorter than 17 in.

Discussion

J. A. Tanney (S.O.S. Cinema Supply
Corp.} : Have you had any experience
with wide-angle lenses of comparatively
short throw?

Mr. Hatch: I understand that there is
a type of lens which has recently appeared
which will give a wide-angle picture with
a very short throw. It is possible that
such an objective system could be coupled
with this projector.

Mr. Tanney: What I had in mind was
its possible ues in TV studios for back-
grounds or in motion picture work for
still backgrounds.

Mr. Hatch: We are going to investigate
those possibilities in connection with this
projector.

Arthur J. Hatch: Arc Slide Projector

337

Proposed American Standard

PH22.90 Aperture Calibration of Motion Picture Lenses

STARTING ABOUT 1940, there has been a
rapidly growing need in the motion
picture industry for a more accurate
expression of the photographic speed of
a lens than is afforded by the simple
/-number ratio. The Proposed Ameri-
can Standard appearing on the following
pages is the product of many years'
industrious and patient effort to achieve
agreement on a standard photometric
method of aperture calibration. It is
published here for 6-month trial and
criticism. All comments should be
sent to Henry Kogel, SMPTE Staff
Engineer, prior to April 15, 1953, along
with a carbon for R. Kingslake, Chair-
man of the Optics Committee.

The problem is essentially this: the
density of a photographic image depends
on (a) the brightness of the subject,
(b) the effective speed of the lens, (c)
the speed of the film, (d) the exposure
time, and (e) processing of the film.
In modern motion picture production
all these factors except (b) are con-
trolled or known to within a few per
cent, but the supposed speed of the lens
may be in error by as much as 60 or
70%. This is caused by loss of light
through surface reflections or direct
absorption in the lens, and occasionally
to incorrect marking of the /-number
scale.

By August 1947, no less than eight
papers on lens calibration had appeared
in this JOURNAL.

The Standards Committee, therefore,
formed a Subcommittee on Lens Cali-
bration to study the whole subject and
to recommend a standard procedure
for measuring the effective photographic
speed of a lens. In October 1949 the
Subcommittee published a report of

their investigations and recommenda-
tions, which became the basis of the
present proposal. The introduction to
the report stated in part: "The demand
for a photometric type of aperture
calibration ("T-stop") is becoming
increasingly felt, and it has the ad-
vantage that diaphragms of any shape,
pentagonal, scalloped or irregular, can
be correctly labeled with as much ease
as a circular one. The presence or
absence of antireflection coatings is
automatically accounted for in the
calibration, and so also are factory
variations in the focal length and in the
iris mechanism. Illumination on the
film in the center of the field will there-
fore be the same for all lenses at the same
T-stop, assuming that the object is a
uniform plane surface perpendicular to
the lens axis. It is implicit, also, that
each lens shall be individually calibrated
if the photometric method is used."

In November 1949 the Subcommittee
was given formal status of its own in the
creation of the Optics Committee under
the chairmanship of Mr. Kingslake.
This Committee achieved agreement on
the final version of the proposal at its
May 3, 1951, meeting and forwarded it
to the Standards Committee for proc-
essing as an American Standard. The
ballot of the Standards Committee on
the question of preliminary publication
brought forth several negative votes, all
of which were based on objections to
paragraphs dealing with some of the
practical applications of T-stops. These
were not fundamental aspects of the
proposal and have therefore been
eliminated, paving the way for its
present publication.

338

October 1952 Journal of the SMPTE Vol. 59

Proposed American Standard

Aperture Calibration
of Motion Picture Lenses

PH22.90

p. 1 of 10 pp.

1. Scope

1.1 The purpose of this standard is to define
the f and T numbers used to express the rela-
tive aperture of a photographic objective. A
second purpose is to establish means for cali-
brating the diaphragms of objectives in both
the f and T systems, with suitable tolerance
specifications.

1.2 The f number of a lens represents a true
geometrical measure of the relative aperture.

1.3 The T number is a photometrically deter-
mined measure of the relative aperture of a
lens adjusted to take proper account of the
lens transmittance, so that the illuminance in
the center of the lens field will be the same for
all lenses at the same T-stop setting. This as-
sumes that the object is a uniform plane diffus-
ing surface perpendicular to the lens axis.

1.4 It should perhaps be mentioned that the
photometric calibration of a lens diaphragm
as contemplated by the T system of diaphragm
marking established by this specification is
only one step in extending the control for the
purpose of producing negatives of a desired
uniform density. The density of a negative is
dependent upon the illumination and reflect-
ance of the object photographed, the correct-
ness of the diaphragm marking, the absorp-
tion of the lens, the accuracy of timing of the
exposure, the uniformity of the emulsion em-
ployed, and complete control of the proces-
sing. The application of the T-stop system is
designed to improve the control as regards
correctness of diaphragm marking and ab-
sorption of the lens. The importance and need
for this particular control increases as the con-
trol of the other factors enumerated is im-
proved.

2. Theory

The illuminance at the center of the

image of a uniform plane extended object
perpendicular to and centered on the lens
axis, when the lens has a circular aperture, is
given by

E = TT t B sin20

(1)

2.2 In this formula: E is the illuminance in
lumens per unit of area; t is the lens transmit-
tance, expressed as the ratio of emerging flux
to entering flux for a beam sufficiently narrow
to pass through the lens without obstruction
by the lens mount; B is the object luminance
in candles per square unit; and 6 is the semi-
angle of the cone subtended by the circular
exit pupil of the lens at the point where the
lens axis intersects the image plane.

2.3 If the lens can be assumed to be apla-
natic, that is, to be free from spherical aberra-
tion and to satisfy the sine condition, and if
the object is very distant, then the value of sin
0 will be given by

sin 0 =

(2)

where Y is the semidiameter of the circular
entrance pupil of the lens and f is the focal
length. The validity of this equation may be
seen by reference to Fig. 1, remembering that
in a lens having the type of correction assumed
in this paragraph, the principal planes of
Gauss are in reality portions of spheres cen-
tered about the axial object and image points,
respectively.

2.4 If the lens aperture is not circular, which
will often occur when the iris is partly closed,
the angle B has no meaning. In such a case,
we may define the effective, diameter, D', of
the entrance pupil in terms of its area, A, by

A = * P'2 (3)

APPROVED

October 1952 Journal of the SMPTE Vol. 59

339

Proposed American Standard

Aperture Calibration
of Motion Picture Lenses

PH22.90

p. 2 of 10 pp.

whence

— 2

(4)

2.5 For an aplanatic lens, we may now re-
place sin 6 by D'/2f, and the image illumi-
nance equation (1) becomes

E - TT t B (D'/202
whence by equation (4), we find

E = t BA/f2 (5)

3. Definition of t Number

3.1 For a lens of the type assumed, having a
circular aperture, which is perfectly corrected
for spherical aberration and satisfies the sine
condition, and which is also assumed to form
an image in air of a very distant object, the f
number of the lens is defined by the equation

f number =-L= -

D 2 sin 00 (6)

where 00 is the semiangle of the cone subtended
by the circular exit pupil of the lens at the
point where the lens axis intersects the plane
of the image of the assumed distant object,
and the entrance pupil has a diameter D.

3.2 If the entrance pupil is not circular, this
relation becomes

/number— — = — /— u\

D' 2V A (7)

following the reasoning of Section 2.4.

3.3 If the aperture is circular, but the lens
does not satisfy the sine condition, then f/D
will not be equal to l/(2sin$). In such a case,
the f number of the lens is to be defined by
l/(2 sin B) rather than by the ratio f/D. This
value is chosen because both the image illumi-
nance and the depth of field of the lens de-
pend directly on sin 0. In such a lens, then, the
marked f number will not be equal to the sim-
ple ratio of the focal length to the diameter of
the entrance pupil.

3.4 The procedure for measuring the f num-
ber of a lens with a distant object is given in
Section 11.

3.5 In terms of f number, equation (1) giving
the image illuminance becomes

E - TT t B/4(f number)2

(8)

4. Effective and Equivalent f Number
of a Lens Used at Finite Magnification

4.1 If a lens with a circular aperture is used
to form an image at a finite magnification m,
the image illuminance will, as always, be
given by equation (1).

NOT APPROVED

340

October 1952 Journal of the SMPTE Vol. 59

Proposed American Standard

Aperture Calibration
of Motion Picture Lenses

PH22.90

4.2 The Effective f number of the lens, which
is to be used to determine the image illumi-
nance by equation (8), is then defined by

Effective f number = /o\

2 sin 8 V'

where #m changes as the magnification m in-
creases.

4.3 For an infinitely thin lens, or for a thick
lens in which the entrance and exit pupils coin-
cide with the first and second principal planes,
respectively, and in which the light beam is
limited only by the iris diaphragm, the Effec-
tive f number will be related to the f number by

(Effective f number for magnification m) —

(f number) (1 + m) (10)

4.4 However, many lenses cannot be re-
garded as being "thin," and in such cases the
Effective f number at a finite magnification
will not* be equal to the infinity f number
multiplied by (1 + m). However, the photog-
rapher knows from long experience that he
should always multiply the marked f number
of a lens by (1 -f m) in order to determine the
Effective f number at a finite magnification m.
Therefore, in order that this procedure can
continue to be used, it is suggested that if a
lens is designed to work at or near some par-
ticular finite magnification m, the aperture
markings should be engraved with 'the "Equiv-
alent f number" defined by

* For example, an afocal lens of symmetrical con-
struction can be used as a printer or copying lens at
unit magnification. The Effective f number is then
equal to the f number of the half system, but since the
focal length of the whole lens is infinite, no meaning
can be given to the / number of the whole system. For
other examples see: R. Kingslake, "The effective aper-
ture of a photographic objective," J. Optical Soc.
Am., vol. 35, pp. 518-520 (1945).

p. 3 of 10 pp.

Equivalent f number ==

[Effective f number at magnification m~I ^ '
L 1 +m J

5. Definition of T Number

5.1 When lenses are marked in accordance
with the f system, differences of value in the
factor t of equation (1 ) are completely ignored,
with the consequence that for a given f -setting
of the diaphragms, even though correctly
marked, the exposures made with different
lenses may vary greatly, this variation arising
from a variation in the number of component
elements of the different lenses and from the
large differences in the values of transmittance
that exist between coated and uncoated lenses.
The T system defined in this section is a new
system of diaphragm graduation designed to
compensate for this variation. With the T sys-
tem of graduation the image illuminance in
the center of the field is independent of the
variations in lens structure enumerated above.

5.2 For a lens used with a distant object, the
T number is defined as the f number of an
ideal lens having TOO per cent transmittance
and a circular aperture, which would give the
same central-image illuminance as the actual
lens at the specified stop opening.

5.3 Hence, for a lens with a circular aper-
ture, following the argument of equation (8),

T number = f number

(12)

and for a lens with an entrance pupil of any
shape and area A, the corresponding formula
is

T number — •

71 03)

5.4 In practice, however, it is expected that
the normal procedure will be to re-engrave
the diaphragm ring on the lens at a series of

NOT APPROVED

October 1952 Journal of the SMPTE Vol. 59

341

Proposed American Standard

Aperture Calibration
of Motion Picture Lenses

PH22.90

p. 4 of 10 pp.

definite T numbers, rather than to measure the
T number corresponding to each of the exist-
ing marked f numbers.

5.5 It may be remarked again that the T
number is a photometrically determined quan-
tity, whereas the f number is a geometrical
quantity. Since the T numbers are determined
photometrically, they automatically take ac-
count of the size and shape of the aperture,
the actual focal length of the lens, the lens
transmittance, and any internally reflected
stray light which may happen to strike the
film at the center of the field (such as in a flare
spot). It is implicit in the T number system of
aperture markings that every lens should be
individually calibrated.

5.6 For a lens designed to be used at finite
magnification, the engraved T number will
correspond to the Equivalent f number defined
by equation (1 1).

5.7 The procedure for measuring the T num-
ber of a lens is given in Section 13.

6. Standard Series of Aperture
Markings

6.1 The diaphragm ring of a lens shall be
marked at every whole stop on either system.
A "whole stop" is taken to represent an inter-
val of double or half the image illuminance,
corresponding to a ratio of \/2 or \f0.5 in the
diameter of a circular lens aperture. By con-
vention, the series of whole stop numbers to
be used are accurately:

0.71, 1.00, 1.41, 2.00, 2.83, 4.00,
5.66, 8.00, 1 1.3, 16.0, 22.6, 32.0

6.2 These marks shall be engraved on the
lens as follows: 0.7, 1 , 1 .4, 2, 2.8, 4, 5.6, 8, 1 1 ,
16, 22, 32. The maximum aperture of the lens

shall be marked with its measured f number or
T number, stated to one decimal place. These
recommendations follow American Standard
Z38.4.7-1943.

6.3 In setting the lens aperture, it is assumed
that the diaphragm ring will always be turned
in the closing direction, and not in the opening
direction; this is to eliminate backlash effects.

7. Subdivision of a Whole Stop

7.1 If it is desired *o subdivide a "whole
stop" interval, we may refer to a fraction S of
a stop, defined so as to yield a ratio of image
illuminance R equal to 2s or (0.5)s. Then, for
any given illuminance-ratio R, the correspond-
ing fraction of a stop will be given by S — (log
R)/(log 2) = 3.32 log R. A few typical ex-
amples are given in the following table:

Fraction of a Stop (S) Illuminance Ratio (R)

one-tenth

one-sixth

one-quarter

one-third

one-half

two-thirds

three-quarters

a whole stop

.072 or 0.932

.122 or 0.891

.189 or 0.841

.260 or 0.793

.414 or 0.707

1.587 or 0.630

1.682 or 0.594

2.0 or 0.5

7.2 When engraving a lens, each whole stop
interval may be divided into three subdivisions
by dots or marks (not numbered), the dots
being at "thirds of a stop," namely, 0.7, 0.8,
0.9, LQ, 1.13, 1.27, L4, 1.6, 1.8, 2,0, 2.2,
2.5, 2JJ, 3.2, 3.6, 4.0, 4.5, 5.0, 5^6, 6.3, 7.1,
8.0, 9.0, 10.0, 11.3, 12.7, 14.2, 16, 18, 20,
23, 25, 28, 32

7.3 The reason for dividing each stop inter-
val into three parts is so that the lens aper-
tures will agree with the exposure-meter mark-
ings stated in American Standard Z52.12-
1944, page 5. The same cube-root-of-two
series is used for the Exposure Index of a film,

NOT APPROVED

342

October 1952 Journal of the SMPTE Vol. 59

Proposed American Standard

Aperture Calibration
of Motion Picture Lenses

PH22.90

see American Standard Z38. 2. 1-1947, page
11. One-third of a stop represents a logarith-
mic illumination ratio equal to 0.1, which is
the transmittance of a neutral density of 0.1.
The ratio of successive circular stop diameters
is equal to \/2 — 1.123.

8. Symbols

8.1 Lenses calibrated on the f system should
bear the designation f/ or f: followed by the
numerals (see American Standard 238.4.7-
1943).

8.2 Lenses calibrated on the T-stop system
should bear the designation T or T— followed
by the numerals.

9. Accuracy of Marking (f System)

9.1 The maximum opening of a lens on the f
system shall be marked with an accuracy of

- 12 per cent of area, or — 6 per cent of
diameter.*

9.2 NOTE: Since in most factories a blanket
calibration is generally used for the f aper-
tures of a complete run of lenses of the same
type, the smaller openings may be in error by

* Z38.4.4-1942 the engraved focal length of lenses
for still picture photography must be within ± 4 per
cent of its true value, and in Z38. 4.7-1 943 the meas-
ured diameter of the maximum entering beam shall
be at least 95 per cent of the quotient obtained by
dividing the engraved focal length by the engraved f
number. Thus by combining these tolerances we find
that the diameter of the maximum lens aperture may
be in error by as much as 9 .per cent. This represents
an error in area of 18 per cent, or one-quarter of a
stop, which is felt to be unnecessarily large for the
maximum aperture. The proposed tolerance on aper-
ture marking for motion picture objective lenses allows
less latitude than that provided for still picture camera
lenses by Sectional Committee Z38 (Photography), be-
cause of the stricter requirements in cinematography
on the same continuous length of film using different
lenses.

p. 5 of 10 pp.

— 25 per cent of area, or — 12 per cent of
diameter (one-third of a stop), particularly in
short-focus lenses. These figures are based on
the assumption that the iris will always be
closed down to the desired aperture and not
opened up from a smaller aperture, to elimi-
nate backlash effects.

10. Accuracy of Marking (T System)

10.1 Since each lens is individually cali-
brated, an accuracy of one-sixth of a stop (10
per cent in illumination or 5 per cent in diame-
ter) becomes entirely possible throughout the
whole range of the diaphragm scale. This is
assuming that the diaphragm is always closed
down to the desired aperture and not opened
up from a smaller aperture, to eliminate back-
lash effects.

10.2 Alternatively, the manufacturer should
be prepared to guarantee this accuracy even
though each stop marking may not be individ-
ually determined.

10.3 It may be of interest to indicate the ap-
proximate magnitude of this tolerance. Since
5 per cent in diameter corresponds to 5 per
cent in f number, a lens of aperture nominally
f/2 may be anywhere between f/1.90 and
f/2.10. A lens nominally f/4.5 may lie be-
tween f/4.28 and f/4.72; and a nominal f/8
may lie anywhere between f/7.6 and f/8. 4.

11. Measurement of t Apertures
(Distant Object)

11.1 The procedure for measuring the f num-
ber of any lens having a circular diaphragm
aperture is described in American Standard
Z38.4.20-1948, paragraph 3.

11.2 If the entrance pupil is noncircular, it
is necessary to measure its area. This may be
done conveniently by mounting a point source

NOT APPROVED

October 1952 Journal of the SMPTE Vol. 59

343

Proposed American Standard

Aperture Calibration
of Motion Picture Lenses

PH22.90

p. 6 of 10 pp.

of light such as a small hole in front of a lamp
bulb, or a 2-watt zirconium lamp, at the rear
focal point of the lens, and allowing the light
beam which emerges from the front of the lens
to fall upon a piece of photographic material.
After processing, the recorded area is meas-
ured with a planimeter and applied in equa-
tion (7). If the lens is too small for this pro-
cedure to be employed, it may be placed in a
suitable telecentric projector working at a
known magnification (a workshop profile pro-
jector is suitable), the back of the test lens be-
ing towards the source of light. The entrance
pupil then will be projected onto the screen
of the projector at a known magnification,
whence its area can be determined with a
planimeter.

12. Measurement of f Apertures
(Near Object)

12.1 To measure the Effective / number of a
lens when used with a near object, it is neces-
sary to determine the angle 6 in equation (9).
This may be done by using a point source of
light at the correct axial object position, and
measuring the diameter of the emerging beam
at two widely separated planes a known dis-
tance apart. A simple computation will enable
the semicone-angle 0 to be determined.

12.2 The Effective f number is defined by
l/(2 sin 6); and the Equivalent f number for
engraving on the lens barrel will then be equal
to the Effective f number divided by (1 + m),
where m is the image magnification. (See Sec-
tion 4.4 above.)

13. Photometric Calibration of a Lens

13.1.1 Since T-stops are based on a meas-
urement of the illumination produced by the
lens at the center of the field, it is first neces-

sary to define the latter term. For the purpose
of illumination or flux measurements, the term
"center of the field" shall be taken to mean
any area within a central circle approximately
3 mm in diameter for 35mm or 16mm frames,
or 1.5 mm in diameter for 8mm frames.

13.1.2 The light used in making the deter-
mination shall be white,* and the sensitivity
characteristic of the photoelectric receiver
shall approximate that of ordinary panchro-
matic emulsion. t It is considered that these
factors are not at all critical and no closer spe-
cification than this is necessary. Obviously
errors will arise if the lens has a strongly selec-
tive transmission, but such lenses would be
undesirable for other reasons.

13.1.3 The incident light shall fill a circular
field whose angular diameter is no more than
10 degrees in excess of the diagonal of the
intended angular field of the lens itself. Dur-
ing measurement, the light shall traverse the
lens in the direction ordinarily employed in
photography.

13.1.4 The lens should be carefully exam-
ined before calibration to ensure that there
are no shiny regions in the barrel which would
lead to flare or unwanted stray light, since
this would vitiate the measurements badly.
The lens surfaces should be clean.

13.2 Corner-to-Center Ratio. Having
calibrated the stop markings of the lens on
the T system by one of the methods to be de-
scribed, the observer may, if desired, deter-
mine in addition the ratio of corner illumina-
tion to center illumination, at full aperture and

* Specifically a tungsten filament lamp operating be-
tween 2900 and 3200 degrees Kelvin.

t A suitable cell is one having an S-3 surface, com-
bined with a Corning 9780 glass filter about 2.5 mm
thick.

NOT APPROVED

344

October 1952 Journal of the SMPTE Vol. 59

Proposed American Standard

Aperture Calibration
of Motion Picture Lenses

PH22.90

p. 7 of 10 pp.

preferably at other apertures also. For this
purpose the 3-mm (or IV-z-mm) hole shall be
used first at the center of the field, and then
moved outwards until its rim is touching the
top and side limits of the camera gate. This
distance is shown in Table I.

Table

Gate, Mm

35(16.03 x 22.05)

16 ( 7.47 X 10.41)

8 ( 3.51 x 4.80)

Radial Shift of Hole, Mm

11.5

4.5

2.0

13.3 Extended-Source Method of
T-Stop Calibration (distant object).

13.3.1 This method of lens calibration has
been described by Gardner13 and Sachtle-
ben,9 the underlying theory being given by
McRae.4 It is based on filling the lens with light
from an extended uniform source, and plac-
ing a metal plate in the focal plane of the
lens with a 3-mm hole (or 1.5-mm for 8-mm
film) at its center. The light flux passing
through the hole is measured by a photocell
arrangement. This flux is then compared with
the flux from the same source passing through
the same hole from an open circular aperture
of such a size and at such a distance from the
plate that it subtends the desired angle 6 re-
ferred to in equation (2) above. The greatest
care is necessary to ensure that the extended
source is really uniform, and also constant
throughout the measurements. The open cir-
cular aperture is used as the "ideal lens with
100 per cent transmittance" referred to in
Section 5.2.

13.3.2 It should be noted that this proce-
dure measures the T-stop Aperture Ratio of the
lens directly, regardless of whether or not the
lens is aplanatic.

13.3.3 In practice, the photocell reading for
each whole T-stop number is first determined

for a series of open apertures, at a fixed dis-
tance from the plate. The lens is then substi-
tuted for the open aperture with the 3-mm
hole accurately in its focal plane, and the iris
of the lens is closed down until the photocell
meter reading produced by the lens is equal
to each of the successive open-hole readings.
The full T-stop positions are then marked on
the diaphragm ring of the lens. The intermedi-
ate third-of-a-stop positions may be found
with sufficient accuracy by inserting a neutral
density of 0.1 or 0.2 behind each open aper-
ture in turn and noting the corresponding
photocell readings.

13.3.4 The following table of aperture di-
ameters may be useful. They are based on a
distance of 50 mm from aperture to plate. (It
is important to remember the difference be-
tween sine and tangent, and that the aper-
ture diameter is not found merely by dividing
50 mm by the T number.)

Table II

Value of 0 =

Cosec~l Diameter of

Desired (2 X T number), Aperture =

T Number Degrees 1 00 tan f). mm

0.5

0.71

1.00

1.41

2.00

2.83

4.00

5.66

8.00

11.31

16.00

22.63

32.00

90
45
30

20.708

14.478

10.183

7.181

5.072

3.583

2.533

1.791

1.266

0.895

100

57.74

37.80

25.82

17.96

12.60

8.88

6.26

4.42

3.12

2.21

1.56

13.3.5 A single set of apertures is sufficient
to calibrate lenses of all focal lengths, since
the only factor involved is sin 9, and that is

NOT APPROVED

October 1952 Journal of the SMPTE Vol. 59

345

Proposed American Standard

Aperture Calibration
of Motion Picture Lenses

PH22.90

fixed by the aperture used. The apertures
should be bevelled to a sharp edge, and well
blackened on both sides.

13.3.6 The extended source should be uni-
formly bright over its useful area to within — 3
per cent. (This can be tested with a suitable
telephotometer, or a small hole in an opaque
screen can be moved around in front of the
source, and any consequent variations in
photocell reading noted.) The source conveni-
ently may be a sheet of ground glass covering
a hole in a white-lined box containing several
lamps mounted around the hole and shielded
so that no direct light from the lamps falls on
the ground glass itself.

13.3.7 The photocell receiver conveniently
may be of the phototube type with a simple
direct-current amplifier.* Care must be taken
to ensure that the phototube sensitivity and
the line voltage do not change between mak-
ing readings on the open aperture and on the
lens itself; to guard against this, some con-
venient turret arrangement is desirable with
the lens on one side and the open aperture on
the other so that the two may be interchanged
and compared immediately with each other
by merely turning the turret.

13.3.8 To measure the corner-to-center il-
lumination ratio, then lens is set in position and
the 3-mm hole and the photocell are displaced
laterally by the desired amount. The photocell
reading is noted at axial and corner positions,

* Suitable systems are the "Electronic Photometer"
model 500 (Photovolt Corporation, 95 Madison Ave.,
New York, N. Y.), and the "Magnephot" (W. M.
Welch Scientific Co., 1515 Sedgwick St., Chicago, III.).
It is felt that a barrier-layer cell, although desirable
for reasons of simplicity, has insufficient sensitivity for
accurate determinations of the smaller apertures un-
less a galvanometer of exceptionally high sensitivity
is employed.

p. 8 of 10 pp.

and the corresponding light ratio found from
a calibration curve of the photocell meter.

13.4 Collimated Source Method of
Lens Calibration.

13.4.1 This method has been described by
Daily n and Townsley,14 the underlying theory
being embodied in Section 5 above. Light from
a small source (a 5-mm hole covered with opal
glass and strongly illuminated from behind) is
collimated by a simple lens, or an achromat if
preferred, of about 15 inches focal length and
2 inches aperture. This gives a collimated
beam which will be focused by the test lens to
form a small disk of light in its focal plane.
This circle of light will be less than the pre-
scribed limit of 3-mm diameter for all lenses
under 9 inches in focal length. Uniformity of
the collimated beam can be checked by mov-
ing a small hole in an opaque screen across
the beam, and any variations in the photocell
reading noted.

13.4.2 For the comparison unit, an open
aperture is used, of diameter equal to the
focal length of the lens divided by the desired
T number. This aperture is first mounted in
front of an integrating sphere with the usual
photocell detector, and the light from the col-
limator is allowed to enter the aperture. The
aperture plate is now replaced by the lens,
the iris diaphragm is closed down to give the
same photocell reading, and the T-stop num-
ber is engraved on the iris ring. The inter-
mediate thirds of stops can be added by using
0.1 or 0.2 density filters as in the method of
Section 13.3.3.

13.4.3 To guard against drift and line-volt-
age variations which might occur between the
readings on the comparison aperture and on
the lens, it is convenient to leave the known
standard aperture in place in front of the
sphere, and to insert the lens into the beam in

NOT APPs?OVED

346

October 1952 Journal of the SMPTE Vol. 59

Proposed American Standard

Aperture Calibration
of Motion Picture Lenses

PH22.90

such a position that the little image of the
source falls wholly within the standard aper-
ture. The meter reading should then remain
the same no matter whether the lens is in or
out of the beam. A second plate with a 3-mm
aperture should be placed over the compari-
son aperture while the lens is in place to stop
any stray light which may be reflected from
the interior of the lens.

13.4.4 It should be noted particularly that if
this method is used, the focal length of the lens
must be measured separately, and a suitable
set of open apertures constructed for use with
it. However, by suitable devices, one single
set of fixed apertures may be used for all
lenses, as described by Townsley.14

13.4.5 It should also be noted that this pro-
cedure measures f number as the ratio of f/D,
and the measurement is thus influenced by the
state of correction of the lens in regard to
spherical aberration and sine condition.

13.4.6 The corner-to-center ratio at any de-
sired aperture can be conveniently determined
by simply rotating the lens through the de-
sired field angle (/> and comparing the photo-
cell reading with its value for the lens axis.
The light-flux ratio can then be read off a cali-
bration curve for the photocell system, and
converted to the desired corner-to-center illum-
ination ratio by multiplying it by cos3<£. (Note
that this procedure will be correct only in the
absence of distortion, but no motion picture
lens is likely to have enough distortion to cause
any significant error.)

13.5 T-Stop Calibration at Finite
Magnification.

13.5.1 To use the extended source method
(see Section 13.3), it is only necessary to
mount the metal plate at the desired image
distance from the lens instead of placing it in

p. 9 of 10 pp.

the focal plane. The open apertures used for
comparison must be calculated to have an
opening corresponding to the desired Equiva-
lent f number multiplied by (1 + m). This is be-
cause we are really comparing the illuminance
given by the lens with the Effective f number
of the open hole, but the engraving must be
done at each standard step of the Equivalent f
number (see Section 1 2.2.)

1 3.5.2 The collimated source method cannot
be used to calibrate a lens at finite magnifica-
tion.

References

General

1 . A. C. Hardy, "The distribution of light in optical
systems," J. Frank. Inst., vol. 208, pp. 773-791, Dec.
1929.

2. A. C. Hardy and F. Perrin, "Principles of Optics,"
McGraw-Hill, New York, 1932, p. 411.

3. L. C. Martin, "Applied Optics," vol. 2, Pitman,
London, 1932, p. 210.

4. D. B. McRae, "The measurement of transmission
and contrast in optical instruments," J. Opt. Soc.
Amer., vol. 33, pp. 229-243, Apr. 1943.

Lens Calibration

5. G. W. Moffitt, "Determining photographic absorp-
tion of lenses," J. Opt. Soc. Amer., vol. 4, pp. 83-90,
May 1920.

6. J. Hrdlicka, "Measuring the effective illumination
of photographic objectives," Jour. SMPE, vol. 14, pp.
531-553, May 1930.

7. D. B. Clark and G. Laube, "Twentieth Century
camera and accessories," Jour. SMPE, vol. 36, pp.
50-64, Jan. 1941; also U.S. Patent 2,334,906 (filed
Sept. 1940, issued Nov. 1943).

8. E. W. Silvertooth, "Stop calibration of photo-
graphic objectives," Jour. SMPE, vol. 39, pp. 119-122,
Aug. 1942.

9. L. T. Sachtleben, "Method of calibrating lenses,"
U.S. Patent 2,419,421 (filed May 1944, issued April,
1947). (Note: This patent is held by RCA, which has
expressed willingness to grant a paid-op license for a

NOT APPROVED

October 1952 Journal of the SMPTE Vol. 59

347

Proposed American Standard

Aperture Calibration
of Motion Picture Lenses

PH22.90

p. 10 of 10 pp.

nominal fee. See Jour. SMPTE, vol. 56, pp. 691-692,
June 1951.)

10. E. Berlant, "A system of lens stop calibration by
transmission," Jour. SMPE, vol. 46, pp. 17-25, Jan.
1946.

11. C. R. Daily, "A lens calibrating system," Jour.
SMPE, vol. 46, pp. 343-356, May 1946.

12. A. E. Murray, "The photometric calibration of
lens apertures," Jour. SMPE, vol. 47, pp. 142-151,
Aug. 1946.

13. I. C. Gardner, "Compensation of the aperture
ratio markings of a photographic lens for absorption,
reflection, and vignetting losses," Jour. SMPE, vol. 49,
pp. 96-110, Aug. 1947; also J. Res. Nat. Bur. Stand.,

vol. 38, pp. 643-650, June 1947 (Research Paper
RP 1803).

14. M. G. Townsley, "An instrument for photometric
calibration of lens iris scales," Jour. SMPE, vol. 49,
pp. 111-122, Aug. 1947.

15. F. G. Back, "A simplified method for the preci-
sion calibration of effective i stops," Jour. SMPE, vol.
49, pp. 122-130, Aug. 1947.

16. F. E. Washer. "Errors in calibrations of the f
numbers," Jour. SMPE, vol. 51, pp. 242-260, Sept.
1948; also J. Res. Nat. Bur. Stand., vol. 41, pp. 301-
313, Oct. 1948 (Research Paper RP 1927).

17. A. E. Murray, "Diffuse and Collimated T-Num-
bers," Jour. SMPTE, vol. 56, pp. 79-85, Jan. 1951.

NOT APPROVED

348

October 1952 Journal of the SMPTE Vol. 59

International Standardization

By F. T. BOWDITCH, SMPTE Engineering Vice-President

ON LAST JUNE 9, 10 and 11 at Columbia
University, the first meetings of Tech-
nical Committee 36 on Cinematography
of the International Organization for
Standardization were held. This is
the standards group charged with the
preparation of world standards in fields
of cinematography, under the Secretariat
of the American Standards Association.
A following report by Henry Kogel
will give details of the several subjects
discussed. We will consider here our
general impressions of this very interest-
ing event.

Contrary to the final feeling of a
worth-while job well done, those of us
from the United States who took part
in this affair did so largely from a sense
of duty to the Secretariat responsibilities
of the ASA. None of us had any pre-
vious experience in international de-
liberations of this sort, and we were
uncertain as to how much could be ac-
complished. At the end of three days
of close association with our foreign
colleagues, however, the opinion was
enthusiastically unanimous that the
meetings had been very much worth
while; the only complaint to come to
my attention concerned the schedule,
in which only two days had been allo-
cated to TC36. Arrangements were
made on the second day to continue for
a third, and everyone felt that a full
week could have been spent with profit;
as a matter of fact, with a series of group
meetings burning the midnight oil on
both Monday and Tuesday evenings, a
good week's work was actually crowded
into those three days.

In addition to the U.S. delegation, the
meetings were attended throughout by

representatives of Canada, France, Ger-
many and the United Kingdom. A
Belgian representative joined us occa-
sionally, and a space was continually
reserved for the U.S.S.R., whose dele-
gates were somewhere about, but
scheduled uncertainly between cine-
matography and other concurrent meet-
ings. The Russians never did visit us,
which was a matter for some disappoint-
ment curiosity-wise, although the com-
plication of a second translation of all
remarks would undoubtedly have slowed
our progress. As it was, the remarks of
the delegate from France, M. Jean Vivie,
were always made in his native tongue,
with frequent pauses for translation
into English; while the remarks of all
other delegates in English were trans-
lated into French for M. Vivie. This
would at first seem to delay things
immeasurably, but we were fortunate
in having a most capable interpreter,
Mr. L. Foy, whose repertoire included
perhaps ten languages any one of which
he could translate extemporaneously
and unhesitatingly into any other. He
soon developed an amazing knowledge
of motion picture technology and so
operated with the highest efficiency.

The formal meetings were opened on
Monday morning, June 9, by Vice-
Admiral G. F. Hussey, Jr., Managing
Director of the ASA. He introduced
D. E. Hyndman, who delivered the
welcoming address, calling attention
not only to the great importance of
international standards in facilitating
world trade, but pointing out the forth-
coming significance of television as an
international force, and predicting a
growing interest of TC36 in world

October 1952 Journal of the SMPTE Vol. 59

349

standards for this specialized form of
motion pictures.

Dr. L. Knopp, delegate from the
United Kingdom and President of the
British Kinematograph Society, then
proposed that the writer be elected
as Chairman of the meeting, which was
promptly done. This responsibility
was approached with some uncertainty,
but was soon exercised with greater
confidence as the fine cooperative spirit
of the delegates became apparent, and
as the bilingual machinery operated
with much greater smoothness than we
had anticipated. Mr. W. Rambal of
the central ISO office in Geneva sat at
the Chairman's right in the first sessions,
to offer helpful advice on parliamentary
matters as needed.

As things developed, the formal
meetings of the whole Committee were
soon abandoned in favor of a series of
six Working Group meetings on as
many different subjects. These were
attended by all the foreign delegates
and by a limited number of U.S. dele-
gates most interested in each particular
subject. Chairmanships of these Work-
ing Groups were delegated to the
French, German and United Kingdom
representatives, as well as to the U.S.,
and all were conducted in a most
efficient manner. Jean Vivie of France,
Dr. Leo Busch and Wilhelm Waegelein
of Germany, and Dr. L. Knopp and
H. L. Griffiths of England worked tire-
lessly and conscientiously with all these
groups, till late at night on Monday and
Tuesday, and starting again early each
morning. Gerald Graham of Canada
was also present, but only as an observer
since his country is not represented as
a full working member of TC36; Mr.
Foy, our indefatigable translator, was
ever-present to bridge the language
barrier. The U.S. delegation of 20
persons, ably headed by Dr. D. R.
White, chairman of ASA Sectional
Committee PH22 on Motion Pictures,
had a somewhat easier time of it, with
a different small number at each group

meeting. The many months of prepa-
ration by PH22 and by the several
Engineering Committees of SMPTE
proved exceedingly helpful here, as did
the active participation of The Motion
Picture Research Council. W. F. Kelley
of the Council cooperated in all the
group meetings, giving much helpful
advice where motion picture studio
considerations were involved.

Minutes of each meeting and copies
of all resolutions were prepared in time
for distribution at the next session,
mimeographed both in French and in
English. This required that an English
version be prepared at the earliest
possible moment. Henry Kogel, Staff
Engineer of SMPTE, was of much
service here, cooperating with J. W.
McNair, Miss Virginia Kelly and Miss
Carolyn Locher of ASA to get all of our
deliberations correctly recorded.

At the final formal meeting of TC36
on Wednesday afternoon, it was agreed
that all the Working Groups should be
continued on a more permanent basis,
under the chairmanships first assigned.
It seems certain that cooperation via
correspondence will now be very much
more effective than before these personal
acquaintanceships were made. Cer-
tainly the foreign delegates gave every
evidence of a high degree of competence
and sincerity, and in all instances were
very well prepared to discuss the various
matters on the agenda.

The U.S. delegates had also come well
prepared and with open minds, as
witness the agreement to recommend
as a World Standard a picture-to-sound
separation of 21 frames for 35mm film.
The present American Standard specifies
this distance to be only 20 frames, and
any change at first seemed to be an alto-
gether futile attempt to change a well-
established U.S. practice. It soon de-
veloped, however, that the U.S. practice
is in fact to use the 21 -frame separation:
projectors are threaded at 20-frames,
but the studios adjust the sound-to-
picture separation on the film to, give

350

October 1952 Journal of the SMPTE Vol. 59

synchronization to an observer seated
50 ft from the screen. Some years
ago this 21 -frame French proposal was
received in the U.S. via correspondence,
and circulated here for comment over
a period of months, with unanimous
agreement that it would be impractical
for the U.S. to change. A half-hour's
direct conversation with the French,
English and German delegates brought
out the fact noted above, that the U.S.
has been using this proposal all along —
only the standard itself needs to be
changed to bring everything into agree-
ment!

The opportunity of serving as the
chairman of this first meeting of ISO/
TC36, although approached with some
uncertainty, is looked back on with
deep appreciation. This was a most
heartening experience, and all who
contributed to these meetings have the
right to feel that the work of TC36 has
now been given a most effective start.
When men of good purpose sit down
together and talk things over, much
can be accomplished, as witness the
following report by Henry Kogel. We
are proud and happy to have played
a part.

Agenda and Accomplishments of
ISO/TC 36 Meeting

By HENRY KOGEL, SMPTE Staff Engineer

THE PRECEDING REPORT on international
standardization by F. T. Bowditch has
clearly outlined the general aspects
of the three-day meeting, June 9-11,
of Technical Committee 36 on Cine-
matography of the International Organi-
zation for Standardization (ISO/TC
36). It is, therefore, the intent to pre-
sent here only the specific details con-
sidered and the concrete results to date.
The draft agenda was considered
first, then amended slightly. It is
given below in its final form along with
the Working Group associated with each
item.

1. Welcoming Remarks, D. E. Hynd-
man

2. Introduction to Those Present, G.
F. Hussey, Jr.

3. Opening Remarks by the Chairman,
F. T. Bowditch

4. Approval of Agenda

5. Review of Scope

6. Dimensions of Raw Stock — Work
Group 1, chaired by D. R. White,
United States

7. Definition of Safety Film — Work
Group 2, chaired by Leslie Knopp,
United Kingdom

8. Emulsion and Sound Record Posi-
tion in Cameras and Projectors —
Work Group 3, chaired by Leo
Busch, Germany

9. Dimensions and Location for Sound
Records and Scanning Area — Work
Group 4, chaired by Malcolm
Townsley, United States

10. Location and Size of Picture Aper-
tures in Cameras, Projectors and
Printers — Work Group 5, chaired
by Jean Vivie, France

11. Standards Relative to Projection
Halls — Work Group 6, chaired by
Leslie Knopp, United Kingdom

12. Review of Program of Work

Bowditch and Kogel: International Standardization

351

In the discussion on scope, the French
delegate proposed a new version. Modi-
fications were offered and the following
scope was approved for submittal to
letter ballot of TC36.

"The committee shall formulate defi-
nitions, dimensions, methods of
measurement and test, and performance
characteristics related to materials and
apparatus used in silent and sound mo-
tion picture photography, in sound
recording and reproduction and in
laboratory work, also, standards relating
to the installation and characteristics
of projection and sound reproduction
equipment.

"Collaboration is to be established
with all other Technical Committees
working on related questions and es-
pecially with the Committees ISO/TC
42 — Photography and ISO/TC46 —
Documentation."

The previous scope 'is offered for
comparison purposes:

"The formulation of definitions, di-
mensional standards, methods of test,
rating and performance characteristics
of materials and devices used in silent
and sound motion picture photography
and in sound recording and processing
and reproduction in connection there-
with. Collaboration is to be established
with other Technical Committees,
especially with ISO/TC46 — Docu-
mentation, in work on photographic
reproduction."

After providing each member nation
an opportunity to make a general state-
ment on agenda items 6-11, the chair-
man appointed Work Group chairmen
and the remainder of the sessions were
devoted primarily to the detailed con-
siderations of the six Work Groups.
The conclusions reached in each Group
are presented below.

Dimensions of Raw Stock

It was unanimously agreed to recom-
mend to ISO/TC36 that the secretariat
prepare a Draft ISO Proposal for letter
ballot action of all members on Cutting

and Perforating Dimensions for 35mm
Motion Picture Positive Raw Stock to
be based upon the American Standard
Z22. 36-1 947 with the changes indicated
below.

(1) Dimension A to read

1 -2-70 + 0.000 . , -2C nn + 0.00

1. 378 _ 0.002 inch 35.00 - o.os mm

(2) Dimension L to read

18.70 ±0.15 inch 475.00 =b 0.40 mm

(3) Dimension R to read

0.50 millimeter, provided that the
secretariat finds that this is the proper
way to express correspondence with
0.020 inch.

(4) Dimension G to be expressed as
shown in the French Standard
NFS 24-003 with the drawing of the
type given therein but with the
format altered to show lines re-
ferring to bottom edges of perfora-
tions rather than center lines.

(5) The footnotes in Z22.36-1947 indi-
cated by an asterisk and a dagger,
and the appendix, are to be deleted.

(6) Dimension symbol "I" to be changed
to "F."

It was also unanimously agreed to
recommend to ISO/TC36 that the
secretariat prepare two Draft ISO
Proposals on Cutting and Perforating
Dimensions for 16mm Silent and Sound
Motion Picture Negative and Positive
Raw Stock, based upon the American
Standards Z22.5-1947 and Z22.12-1947,
with the following changes:

(1) Dimension A to read

0.628 ± 0.001 inch 15.95 t HI mm

(2) The drawing used to show dimension
G in Z22.5 to follow French practice
paralleling the 35mm presentation
adopted from the French Standard
NFS 24-003, Dimensions of 35mm
Positive Raw Stock, With Positive
Perforations.

(3) Dimension symbol "I" to be changed
to "F" in Z22.5.

(4) Omit notes indicated by asterisk
and dagger.

352

October 1952 Journal of the SMPTE Vol. 59

(5) Omit appendix.

(6) Add a new note reading
"Experience shows that it is common
for film to expand when exposed to
high relative humidity. Allowance
should be made for this factor in
equipment design and in no case
should the equipment design fail to
accommodate film width of 0.630
inch, 16.00 mm."

A specification for film thickness
discussed by the working group but
no agreement was reached. The matter
was left for further discussion and study.

Definition of Safety Film

It was initially agreed that an inter-
national standard for the definition, test
and identification of safety film should
be established.

One of the U.S.A. delegates believed it
would be desirable that any ISO
standard for 32mm, 16mm and 8mm
motion picture film should stipulate the
use of a safety base only. The proposal
appeared to raise national statutory
and legal questions which would call
for investigation and consideration.

The working group noted that the
research which had been conducted in
the United Kingdom had established a
simple form of test which might replace
the more elaborate laboratory tests of
the current American Standard Defini-
tion for Motion Picture Safety Film,
Z22.31-1946. A demonstration of the
apparatus was given and the members
thought the United Kingdom test
worthy of study. The United Kingdom
undertook to prepare and circulate
working drawings and particulars to
enable each country to make its own
apparatus and carry out confirmatory
tests.

France and Germany, however, de-
sired the earliest possible establishment
of an international standard and sug-
gested that the current American Stand-
ard, which was virtually a reproduction
of the ISA proposal of 1936, should be

considered for adoption by the ISO
for a three-year period. While not
seeing any urgent need for this, the
United States representatives said they
would not wish to oppose the adoption
of this course. The United Kingdom
delegates had no power to commit their
country but only to express the view that
the 1936 ISA proposal was too elaborate,
was out-of-date and the time was ripe
for a new specification to be formulated.

It was understood that the ISO was
willing to circulate ISA proposals and
recommendations which could be used
nationally pending the agreement on an
international standard.

Agreement was finally reached that
the Definition for Motion Picture Safety
Film, Z22.31-1946, be submitted to
ISO/TC36 for letter ballot action.

Emulsion and Sound Record Positions
in Cameras and Projectors

The working group agreed to recom-
mend to ISO/TC36 that the secretariat
prepare a Draft ISO Proposal in-
corporating the technical content of the
American Standards listed below with
the modifications indicated:

Emulsion and Sound Record Positions

in Camera for 35mm Sound Motion

Picture Film, Z22.2-1946,
Emulsion and Sound Record Positions

in Projector for 35mm Sound Motion

Picture Film, Z22.3-1946,
Delete paragraphs 2 and 3, reference
to guided edge and footnote. Add
identification of sound record (shaded
area).

Emulsion Position in Camera for 16mm

Silent Motion Picture Film, Z22.9-

1946,
Emulsion Position in Projector for Direct

Front Projection of 16mm Silent

Motion Picture Film, Z22. 10-1 947,
Emulsion Position in Camera for 8mm

Silent Motion Picture Film, Z22.21-

1946,
Emulsion Position in Projector for Direct

Front Projection of 8mm Silent

Bowditch and Kogel: International Standardization

353

Motion Picture Film, Z22.22-1947,
Delete paragraph 2 and footnote.

Emulsion and Sound Record Positions
in Camera for 16mm Sound Motion
Picture Film, Z22. 15-1 946,
Delete paragraph 2, footnote and ref-
erence to guided edge. Also delete
paragraph 3, but the technical substance
of this paragraph is considered suitable
for incorporation in a more suitable
place. Add identification of sound
record (shaded area).

With regard to Z22. 16-1 947, the
working group decided that at present
it did not seem desirable to consider
this for international adoption since
prints were made with the emulsion
position on either side and there was
little likelihood of universal acceptance
of a single standard at this time.

The working group discussed at some
length the question of projection speed
of 24 or 25 frames per second, but did
not reach any decision.

Dimensions and Locations for Sound
Records and Scanning Area

Work Group 4 recommended that
five American Standards be prepared
by the secretariat for circulation as
Draft ISO Proposals, two without
change :

Z22.69-1948, Sound Records and Scan-
ning Area of Double-Width Push-Pull
Sound Prints, Normal Centerline
Type,

Z22.70-1948, Sound Records and Scan-
ning Area of Double-Width Push-Pull
Sound Prints, Offset Centerline Type ;

and three with the modifications in-
dicated below:

Z22.40-1950, Dimensions and Locations
for Sound Records and Scanning
Area of 35mm Sound Motion Picture
Prints

(1) The distance from the edge of the
film to the centerline of the sound
record shall be changed from 6.17 ±

0.02 mm to 6.19 ± 0.02 mm (0.244 ±
0.001 in.).

(2) The distance from the edge of the
film to the inner edge of the printed
area shall be changed from 7.75 ±
0.05 mm to 7.83 ± 0.05 mm (0.308 ±
0.002 in.) . (This change was proposed
by the French delegate on the basis
that difficulties are being experienced
in France with a white line between
sound track and picture printed areas.
The United Kingdom delegation re-
served judgment on the dimension
in (1) and (2) above, but approves
the circulation of the draft.)

(3) In the specification "Distance
between sound and corresponding
picture" change "20 ± J frames" to
"21 frames ± ± frame." (When the
distance from the center of the pro-
jector gate to the sound scanning point
is 20 frames, the picture and sound
will be in synchronism for an observer
at a distance of 50 feet, and with
French practice, which is based on a
measured distance of 21 frames be-
tween picture and sound on the film
itself, and therefore allows for syn-
chronizing the picture to suit an aver-
age audience size.)

(4) Delete the third footnote.

(5) Delete the dimension and all
reference to the height of the scanned
area.

Z22.41-1946, Sound Records and Scan-
ning Area of 16mm Sound Motion
Picture Prints

(1) Change the tolerance on the
width of the sound record for full
width variable-density record from
0.080 ± 0.001 in. to 0.080 ± oiooi in.

(2) Delete the present footnote.

(3) Add a new footnote reading:
"The width of the 16mm sound record
is derived by reducing the corre-
sponding 35mm dimensions by a ratio
of 1.2 to 1.0 in.

(4) Add a new paragraph : "Distance
between sound and corresponding
picture — the sound record shall pre-

354

October 1952 Journal of the SMPTE Vol. 59

cede the center of the corresponding
picture by a distance of 26 frames ±
| frame."

PH22.86, Dimensions for 200-Mil Mag-
netic Sound Tracks on 35mm and
17^mm Motion Picture Film (a
Proposal well on its way to becoming
an American Standard).

(1) Revise the drawing and dimen-
sions to show a dimension from the
outer edge of the sound record area
to the edge of the film 6.0 ± 0.05
mm (0.236 ± 0.002 in.) on each edge
of the film, and delete all other di-
mensions and all reference to the
track in the center of the film, re-
numbering Track 3 to Track 2.
(The United Kingdom delegation
was unable to associate itself fully
with this resolution as being the best
solution of the current practices in
America, France and in the United
Kingdom, and offered alternative
proposals (which, however, were
not accepted) on the dimension of
0.345 inch ± 0.005 or 0.345 inch ±
0.006, as the location of the centerline
of the sound record relative to the
edge of the film.)

(2) Delete paragraph 7.

(3) Add a note to Paragraph 6:
"When the film is turned end for
end, Track 2 occupies the position of
Track 1."

Location and Size of Picture Apertures
in Cameras, Projectors and Printers

The chairman of Group 5 has not as
yet submitted the report of the con-
clusions reached by his group. This
information will be published in a
future issue of the Journal as soon as
it is received.

Standards Relating to Projection Halls

The members of Work Group 6 had
each presented at their meeting a sum-
mary of the requirements and values in
their published and draft standards on
the subject of screen brightness. Refer-
ence was also made to the resolution

of the CIE (International Commission
on Illumination) at its meeting in
Stockholm in 1951. It was agreed to
restrict discussion to enclosed cinema
auditoriums.

The members noted that the various
countries were now giving consideration
to such factors as : the screen brightness
measurement made from any seat in the
auditorium, the diversity of luminance
between the side and center of the
screen, interference of luminance by
stray light, the method of measurement
and the type of instruments to be used.
The views of the delegates on these
questions were diverse and in some of the
countries research and investigation
were still proceeding.

Differing opinions were also expressed
as to the desirability of adopting the
luminance range and the diversity factors
of the CIE Stockholm meeting. It was
noted that the United States and the
United Kingdom expressed their lumi-
nance values in foot-Lamberts while
France, Germany and the CIE resolu-
tion expressed values in metric units.
It was also noted that, notwithstanding
these divergencies, the quantitative dif-
ference in the various specifications and
in the CIE resolution were not great.

In view of the research and investi-
gation still proceeding in the various
countries, it was the general consensus
that it was not opportune at the present
ISO/TC36 meeting to attempt to
draft an ISO proposal. It was agreed,
therefore, that each country should
proceed with its own investigations and
revision of its own standards, if desired,
and that there should be a postal ex-
change of information between the
countries, so that at the next meeting of
ISO/TC36 the present discussions
might be resumed and an ISO proposal
drafted.

The working group regretted that
time did not permit any discussion on the
remaining subjects such as projection
rooms and projection screens listed under
item 11 of the agenda.

Bowditch and Kogel: International Standardization

355

Organization of the San Francisco Subsection

This brief outline of the organization of the
San Francisco Subsection of the Society
may be of interest and assistance to
similarly situated groups in other localities.

The San Francisco Subsection began
as the expression of a desire of a number
of the individual members in the Bay
Area to have some form of local activity
and participation in the affairs of the
Society. The Conventions held alter-
nately in Hollywood provided some
advantage but in general most of the mem-
bers gained from their membership only
the published Journal.

Many informal discussions had been
held during 1951 regarding the prac-
ticability of setting up some form of local
group and these culminated in the forma-
tion of the present organization. Edwin
W. Templin and Dr. Charles R. Daily
were particularly helpful in presenting
our plan to the Board of Governors and
securing its approval. The Constitution
of the Society does not specifically provide
for subsection organization but neither
does it forbid it, and, by the latter liberal
view, the San Francisco group was au-
thorized to form the subsection of the
Pacific Coast Section at the meeting of
October 13, 1951.

Upon receiving formal notice of this
action, all of the members of the Society
residing in the Bay Area were notified by
mail and the organizational meeting of the
subsection was held November 30, 1951.
Dr. Daily addressed the group at this
meeting and acted as chairman, represent-
ing the parent section. Election of officers
resulted in the following roster for 1952:

Chairman, Paul A. Williams
Vice-Chairman, William A. Palmer
Secretary-Treasurer, George Mathiesen
Program Chairman, John B. Steiger

During the first half of the year the sub-
section has held three meetings, the
programs of which were as follows :

February 21: "Production of a Pilot
Kinescope for the Standard Hour" pre-
sented by a panel consisting of Warren
Andersen, A. F. Michaelis and W. A.
Palmer.

356

April 17: "TV Picture Sizes," a tape
recording of papers and discussion from a
meeting of the Pacific Coast Section in
Hollywood.

May 22: "Creative Directions in Color
Photography" presented by Ralph Evans
of Eastman Kodak Company.

Attendance at these meetings has been
from 20 to 50, which, although perhaps
not too impressive, represents a large
percentage of the total group membership.

Although there was no expressed plan
of suspending meetings during the summer,
the usual circumstances have conspired
to prevent or delay the fulfillment of our
anticipated plans. Meetings are planned
for the fall and winter and we hope to end
the first year of operation at a peak of
activity.

The effect of an actively functioning local
group on membership recruiting activity
has been very gratifying. It is conserva-
tively estimated that we have added twice
the number of new members since be-
ginning local operation compared with
the previous like period. It is also
interesting to note that, although the
present interest in the television field has
probably encouraged activity and increased
our local membership, there has been
enthusiastic interest among members in
the motion picture industry.

Whether or not the time is ripe for the
San Francisco group to plan on an early
change to independent section operation
cannot yet be determined. At the end
of this year officers will be elected for the
coming term and that question fully
discussed.

We have not been as active as we had
hoped but we are certain that our activity
will increase rather than diminish. It
would be a real help if more assistance
could be provided in securing program
material. The experiment we made with
the use of tape recorded material was con-
sidered successful but for some reason or
another we have had some difficulty in
arranging for additional recorded program
material. It is noted that the IRE Audio
Group has set up a similar plan with a

central tape exchange and this method
might be worth consideration.

The Subsection expenses are a very
minor consideration, for, aside from the
cost of mailing program announcements,
no other expense has been incurred. The
parent Section advanced a sum sufficient
to cover this and other incidental expense.
Meeting places, projection or reproduction
equipment and preparation of meeting
notices have been provided by various
members through the courtesy of their
business connections.

We are firmly of the opinion that the

Society ' as a whole and its individual
members have much to gain by establish-
ment of other subsections. The time has
long since passed when New York and
Hollywood represented a concentration
of motion picture and television activity
to the exclusion of all other areas. The
Society should provide some service to its
members in other areas beyond the pub-
lication and distribution of its Journal and
we are of the opinion that the organization
plan we have followed provides a means
toward that end. — Paul A. Williams, 341
Hazelwood Ave., San Francisco 12, Calif.

Book Review

Color in Business, Science and
Industry

By Deane B. Judd. Published (1952) by
John Wiley, 440 Fourth Ave., New York
16. 401 pp. 106 illus. 6 X 9| in.
Price 16.50.

Here is a most useful and valuable book
by Dr. Deane B. Judd, Chief of the
Colorimetry Unit of the National Bureau
of Standards. During his twenty years
with the Bureau he has come in contact
with hundreds of industrial colorimetric
problems. This book reflects his great
experience along these lines as well as
the many contributions which Dr. Judd
has made to the science of color. It is
an ambitious undertaking to attempt a
book on color that would appeal to busi-
ness, to science, and to industry; but
through Dr. Judd's long association with
all three groups he has succeeded re-
markably well.

The businessman may enjoy the very
readable Part I with its emphasis on the
eye, the customer, and what the customer
sees. He may then profit by scrutinizing
the excellent introductions and summaries
in each of the other sections in the re-
mainder of the book, leaving the study of
the technical details in these sections to
others. However, industrial engineers and
research workers in the field of color will
find the entire work valuable because of
the fusion of the practical problems with
their theoretical aspects and the engineer-

ing or technical solutions to them. In
fact, the book is mainly directed at this
group, and excels any other work in telling
the story of the tools and techniques
available to workers in the field.

The book is divided into three parts.
Basic facts pertaining to the science of
color are given in Part I. Here the
author explains the functioning of the eye,
the characteristics and effects of abnormal
vision, the methods of color matching,
and the aspects of color. It is clearly
shown that perception of color bridges
many sciences. This is, however, treated
in practical fashion as shown by the
section titles: "Chemical — Pigments and
Dyes," "Physical — Radiant Energy in
the Spectrum," "Psychological — The Cus-
tomer's Angle," and "Psychophysical —
How to Predict What the Average Cus-
tomer Will See."

Part II, entitled "Tools and Tech-
niques," comprises by far the largest
portion of the book. Here are set down
the principles and practices for spectro-
photometry, colorimetry and colorimeters,
reproduction of pictures in color, color
standards, uniform color scales, and color
languages. Some 130 pages are devoted
to these last three. He gives an unusually
fine presentation with clear explanations
and evaluations of available sets of color
standards for specifying or matching color,
such as the Munsell Book of Color, the
Villalobos Colour Atlas, the Color Har-
mony Manual, and other systems. Color

357

cards or standards provided by various
segments of industry such as the textile,
printing ink, or paint industries, are also
described. The glossary of color terms
at the end of Part II will be most useful
in that it collects in one place the terms
and definitions for the most important
color concepts used in American industry.

Part III, "The Physics and Psycho-
physics of Colorant Layers," thoroughly
explores techniques for determining or
forecasting the gloss and opacity or hiding
power of colored layers. The major por-
tion of this part is given over to the
Kubelka-Munk analysis as applied to
dyed textiles, paints, papers or pigmented
plastics. Several mathematical tables
necessary for such analytical solutions are
included in the appendix which should
prove useful to those interested in these
materials.

There is an excellent selection of ref-
erences which includes the important
work in the field for those who will wish
to pursue the subject further, and also a
fine index.

Members of the SMPTE may be par-
ticularly interested in the section entitled
"Reproductions of Pictures in Color,"
in which Dr. Judd outlines the general
problem and also demonstrates by a prac-
tical example the use of the CIE tristimulus
values and the color triangle to select
practical working primaries, and thence
to the determination of camera sensitivities
for a typical color television system. This
reviewer was particularly impressed by
Dr. Judd's reasonable approach to the
old question of the importance of art
versus science in color reproduction. To
quote :

"An important question in reproduction
of pictures in color is color fidelity — how
faithfully the colors of the original scene
are reproduced. This is not the whole of
the problem of producing pictures that
the public will like. We know too little
about what makes us see objects and
people from the mosaic of colored patches
presented to the eye from real scenes to
state with confidence that a completely
faithful reproduction (not yet achieved,
by the way) would always look good. In
fact, there are some who take the position
that perfect color fidelity usually leads
to poor pictures and should be avoided on
purpose. They say that intentional sys-
tematic deviations from fidelity can make
the picture better than the original itself.
This is adding art to science. But even
if you intend to try to improve on the
original scene, it is a great help to have a
faithful reproduction to start with. You
could not get very far with intentional
improvements if the basic color fidelity
of the picture was so poor that it would not
yield any reds, for example, in the picture,
or so poor that greens in the original
scene were rendered as reds in the picture.
So, reasonably faithful reproduction of
colors must be built into any reproduction
system, even if the final aim is to improve
artistically upon the original scene by in-
tentional deviations from color fidelity."

With the increasing emphasis on color
in motion pictures and television, an
understanding of this concept is important.

This book is highly recommended to
all interested in color and its industrial
applications. — L. M. Bearing, Technicolor
Motion Picture Corp., 6311 Romaine St.,
Hollywood 38, Calif.

Journal on Microfilm

Microfilm editions of the Journal of the SMPTE are now available to members and
subscribers from University Microfilms, Ann Arbor, Mich., which records more than
700 periodicals. Journal Volumes 54 and 55 (1950) are priced at $4.15 and Volumes 56
and 57 (1951) cost $4.00 (this is the year that the Journal switched to the two-column
format, with a saving in pages). If there were enough demand for it, University Micro-
films would make positives for the years 1941-49. The present price for such positives is
about a half cent per page, but this would be reduced with a larger number of customers
to share the cost of the negatives. Readers may address inquiries to University Micro-
films, 313 North First St., Ann Arbor, Mich.

358

Members and the Journal Overseas

Echoes of the impact of the SMPTE and
the Journal come back to us from overseas
now and then — and we should record
them, just as we have been able earlier in
this Journal to record the exchange of
bases for international standardization.

A recent letter from Vernon Jarratt,
Manager of Mole-Richardson (Italia),
Rome, prompts some quotation and nota-
tion about the Society in Italy:

"What I have noticed is the considerable
increase in the circulation of the Journal
in the three years that I have been a
member. This is probably more notice-
able to someone like myself who is in
constant touch with the various technical
heads than visible in your list of subscrip-
tions, as a good deal of the 'circulation' is
the literal circulation of a copy that travels
from office to office and from desk to desk.

"When Mole-Richardson opened here
in 1948 the technical side of the industry
was in a pretty primitive state all around,
as indeed is obvious to anybody who, from
a purely technical point of view, considers
the films such as Rome Open City, Four Steps
in the Clouds, Paisa, and the other films
with which Italy first made its postwar
name. This was partly due to destruction
and looting during the war, and partly
to the Fascist policy of autarchy which
threw the Italian industry very much back
on its own resources.

"One incidental result of this was rather
amusing. When we brought in the first
'Brutes' in 1949 most cameramen refused
to touch them, insisting that they could
manage quite well with the 150-amp arcs
to which they were already accustomed.
One or two of the more enterprising (who,
incidentally and not surprisingly, are also
members of the Society) broke the ice,
however, and the rest rapidly followed.
The difference was very noticeable when,
last year, we introduced Compact Source
(mercury-cadmium) equipment for the
first time. Although this represents a
much bigger technical difference from
previously existing equipment than the
Brute, which is after all only a larger
carbon arc, the Compact Source equip-

ment was accepted with much less re-
sistance. Now, and thanks certainly in
part to the Journal, there is a much livelier
interest in technical developments."

Mr. Jarratt's letter prompted a few
moments research which revealed the
following thirteen members with addresses
in Italy.

Baume, Alessio, Manager, 16mm, Metro-

Goldwyn-Mayer, Italy. Mail: Via Camil-

luccia 71, Roma, Italy. (A, 1947)
Carrara, Enrico, Vice-President, Cetra Records,

Corso Pesihiera 10, Torino, Italy. (A, 1949)
Cambi, Enzo, Consulting Engineer, Cinecitta

Studios; Lecturer, National Research Council

(Italy) and Leghorn Naval Academy. Mail:

Via Giovanni Antonelli 3, Rome, Italy. (A,

1950)
Corradi, Amerigo, Tecnostampa, Via Al-

balonga 38, Rome, Italy. (A, 1950)
Dalle Rose, Demetrio D., Manager, Western

Electric Company of Italy, Inc. Mail: Via

Oglio 9, Rome, Italy. (A, 1946)
De Renzis, Francesco, Manager, Westrex Co.

(Italy), Piazza Lovatelli 1, Rome, Italy.

(A, 1945)
Innamorati, Libero, Dr. Ing., Centro Speri-

mentace Cinemato-Grafia. Mail: Via Sa-

trico 43, Rome, Italy. (A, 1936)
Jarratt, C. V., Manager, Mole-Richardson

(Italia), Via Dell'Arco Di Travertine, No. 57,

Rome, Italy. (A, 1949)

Marzari, Antonio, Cameraman, Shorts Producer

and Director, Veneziana Cortometraggi, S.

Marco 557, Venice, Italy. (A, 1947)
Monteleoni, Giulio Cesare, Ispettore Tecnico,

Soc. Ferrania. Mail: Via Crispi 10, Rome,

Italy. (A, 1948)
Portalupi, Piero, Director of Photography in

Motion Picture Production, Lux Film.

Mail: Viale Bruno Buozzi 83 int F, Rome,

Italy. (M, 1952)
Robecchi, Franco, Sound Engineer, Titanus.

Mail: Piazzale Metronio 1, Rome, Italy.

(A, 1948)
Trentino, Victor, Motion Picture Sound

Engineer, 2 Via Ipponi, Rome, Italy. (A,

1945)
Zambuto, Mauro, Technical Director, Scalera

Films. Mail: Italian Films Export, 1501

Broadway, New York 36, N.Y. (M, 1952)

359

Obituary

Nathan Levinson died on October 18 at
his home in Hollywood. He was 64. He
was head of Warner Brothers sound de-
partment and well known for his work
in the early days of sound motion pictures.
He was credited, with the late Samuel L.
Warner, with responsibility for the first
sound film projection which was the
musical score for Don Juan exhibited in
New York in August 1926. Voice re-
production followed in 1927 with the
release by Warner Brothers' Vitaphone
Corp. of Al Jolson's The Jazz Singer.

Born in New York City he was early
at work as a Western Union messenger.
After learning telegraphy "on his own,"
Nathan Levinson became a civilian radio
engineer with Marconi and for the Navy.
World War I found him a Signal Corps
Major in command of the Fort Monmouth,

N.J., Laboratories. In the early twenties
he was a commercial engineer in the radio
broadcast field for the Western Electric
Co. on the Pacific Coast and in 1925 he
was managing director of San Francisco's
radio station KPO. A year later he was
Warner Brothers' sound director and
western division manager of Vitaphone
Corp.

Col. Levinson was a Fellow of this
Society and most recently served as a
member of the Theater Television Com-
mittee. He was awarded the Society's
Samuel L. Warner Memorial Medal in
1948 "for his outstanding work in the
field of motion picture sound recording,
the intercutting of variable-area and
variable-density sound tracks, the com-
mercial use of control track for extending
volume range, and the use of the first
sound-proof camera blimps."

He was interested and instrumental in
a variety of developments. For instance,
the use of 16mm motion pictures with
high-speed development, while not an
original idea with Col. Levinson, was,
under his guidance, commercialized for
recording race-track events. During
World War II the Navy asked Warner
Brothers to take over the manufacture of a
special combat camera and responsibility
for it was added to Col. Levinson's direc-
tion of Warner Brothers' sound depart-
ment. He was a Warner Brothers' repre-
sentative on the Research Council for the
past twenty years. In 1941, Col. Levinson
was given a special award by the Academy
of Motion Picture Arts and Sciences for
"outstanding service to the industry and
to the Army." The next year he received
the Academy Award for the best sound
recording, that of Yankee Doodle Dandy.

SMPTE Lapel Pins

The Society will have available for mailing after September 15, 1952, its gold and blue
enamel lapel pin, with a screw back. The pin is a ^-in. reproduction of the Society
symbol — the film, sprocket and television tube — which appears on the Journal cover.
The price of the pin is $4.00, including Federal Tax; in New York City, add 3%
sales tax.

360

New Members

The following members have been added to the Society's rolls since those last published. The
designations of grades are the same as those used in the 1952 MEMBERSHIP DIRECTORY.

Honorary (H)

Fellow (F)

Active (M)

Associate (A)

Student (S)

Appleby, Fredericka, New York University.

Mail: 810 Broadway, Newark, N.J. (S)
Bell, Charles L., Supervisor of Production

(East Coast), The Jam Handy Organization,

1775 Broadway, Rm. 407, New York 19,

N.Y. (A)
Birdno, George M., TV Engineer, National

Broadcasting Co. Mail: 11028 Moorpark

St., North Hollywood, Calif. (A)
Bowman, Lester H., Director of Technical

Operations, CBS-KNX-KNXT, Columbia

Broadcasting System, Inc., 6121 Sunset Blvd.,

Hollywood 28, Calif. (M)
Brooke, Ned R., Film Director, WSAZ-TV,

West Virginia Bldg., Huntington, W. Va.

(A)
Brunswick, Lawrence F., Optical Engineer,

Colorvision, Inc. Mail: 11190 Valley Spring

PL, North Hollywood, Calif. (M)
Burton, John W., Motion Picture Photographer,

Engineer, U.S. Navy, llth Division, Naval

Air Station, Anacostia 20, D.C. (A)
Butler, Elliott H., City College, Film Inst.

Mail: 470 Audubon Ave., New York 33,

N.Y. (S)
Cannella, Ben R., Cameraman, Picture House,

Inc. Mail: c/o Reta Jensen, Mountain,

Wis. (A)
Challacombe, Jack A., Foreman, Sensitometric

Control Dept., Cinecolor Corp., 2800 W.

Olive, Burbank, Calif. (A)
Chullasapya, Brig. Gen. Dawee, Royal Thai

Air Force, Bangkok, Thailand. (M)
Cochran, Lee W., Director, Bureau of Audio-
Visual Instruction, State University of Iowa,

Iowa City, Iowa. (M)
Connor, Roland E., Equipment Engineer,

Eastman Kodak Co. Mail: 16 Lilac Dr.,

Rochester, N.Y. (M)

Cotlov, Nelson, Projectionist, South City Drive-
in; Film Editor, Capital Film Exchange.

Mail: 819 Parmley Ave., Yeadon, Pa. (A)
Craig, Stephen R., Motion Picture Sound

Engineer, Great Commission Films, Inc.

Mail: 3455 Meier St., Venice, Calif. (A)
de Forest, Allan F., Manager, Special Services,

Peerless Film Processing Corp. Mail: 11

Bank St., New York, N.Y. (A)
Embree, Lee R., Motion Picture Photographer,

U.S. Air Force. Mail: 265 E. Montecito

Ave., Sierra Madre, Calif. (A)
Fernandez, R., Carlos, Sound and Theater
Engineer, J. Glottmann S.A. Mail: Carrera
19, #47-23, Bogota, Colombia. (M)

Foy, Walter L., Chemist, E. I. du Pont de

Nemours & Co. Mail: 78 Van Liew Ave.,

Milltown, N.J. (M)
Grunwald, Robert, President, Harwald Co.,

Inc., 1261 Chicago Ave., Evanston, 111. (A)
Hann, William G., Film Technician, Cinecolor

Corp. Mail: 11626 Chandler Blvd., North

Hollywood, Calif. (A)
Harris, Franklin S., Jr., Physicist, Department

of Physics, University of Utah, Salt Lake

City 1, Utah. (M)
Hauser, Willard H., Chief Engineer, WBL-

TV, Westinghouse Radio Stations, Inc., 1170

Soldiers Field Rd., Lexington, Mass. (M)
Howell, Joseph E., Chief Engineer, WDSC.

Mail: 604 Carthage Rd., Lumberton, N.C.

(A)
Hubbard, Ray A., Art Director, KPIX. Mail:

74 Alta Vista, Mill Valley, Calif. (M)
Izquierdo, Mike, Sound Engineer, Cines

Alcazar S.A. (International Amusement Co.).

Mail: 7539 Taxco Rd., El Paso, Tex. (A)
Jackson, Robert M., Animation Photographer,

The Calvin Co. Mail: 4117 Mercier St.,

Kansas City 2, Mo. (A)
Jackson, William J., Chief Engineer, KEYL,

San Antonio Television Co., Transit Tower,

San Antonio, Tex. (M)
Jewell, James, Television Engineer, Motion

Picture Cameraman, WWJ-TV. Mail:

26191 Allen Rd., Trenton, Mich. (M)
Jost, Hans Joachim, Albrechtstrasse, 78, Berlin-

Steglitz, Germany. (M)
Kaak, Henry W., Jr.. Assistant Technical

Adviser, Camera Dept., Technicolor Motion

Picture Corp. Mail: 7745 Agnes Ave., North

Hollywood, Calif. (A)
Kelly, Michael, Motion Picture Cameraman,

Northrop Aircraft Co. Mail: 6109£ Vic-
toria Ave., Los Angeles 43, Calif. (M)
Klein, Max R., Director, Army Film Library

Services, U.S. Army (Civ. Service). Mail:

1387 Linden Ave., Highland Park, 111. (M)
Kraus, Robert W., Apprentice, Motion Picture

Laboratory Technician, Precision Film

Laboratories. Mail: 2006 Benson Ave.,

Brooklyn, 14, N.Y. (A)

Kuriyama, Tetsuzo, Managing Director, Nip-
pon Onkyo Seiki Co. (Japan Sound Equip-
ment). Mail: c/o R. A. Haines, FEC Mo-
tion Picture Div., Special Services Section,
GHQ, Far East Command, APO 500, c/o
P.M., San Francisco, Calif. (A)

361

Laeser, Phillip B., Television and Radio Engi-
neer, The Journal Co., WTMJ-TV, 720 E.
Capitol Dr., Milwaukee, Wis. (M)

Lapins, Theodore, Engineer, H. de Lanauze
Cinema Distribution & Service. Mail: Isle
Perrot, Terrace, Quebec, Canada. (A)

Lewis, Earl W., Radio-Television Engineer,
WTVJ. Mail: 795 Harbor Dr., Key
Biscayne, Miami 49, Fla. (M)

Lewis, J. Kenneth, Recording Engineer, U.S.
Navy Dept., Bureau of Ships. Mail: 9209
48 Ave., College Park, Md. (A)

Lorenc, Richard M., Electronics Text Develop-
ment Draftsman, De Forest's Training, Inc.
Mail: 6925 W. Highland Ave., Chicago 31,
111. (A)

Lotz, H. Walter, Factory Superintendent,
Motiograph, Inc., 4431 W. Lake St., Chicago
24, 111. (M)

Love, Nathan, Superintendent Technician,
Federal Engineering Co. Mail: 376 E.
Eighth St., Brooklyn 18, N.Y. (A)

Mejid, Kerim, Motion Picture Cameraman,
Ministry of Education (Iraq). Mail: Audio-
Visual Center, 121 College PL, Syracuse,
N.Y. (A)

Metzger, William H., Motion Picture Tech-
nician, Ansco, Div. Gen'l Aniline & Film
Corp., 405 Lexington Ave., New York, N.Y.
(A)

Obata, Toshikazu, Director, Dentsu Motion
Picture Co. Mail: 104 Mukoyama-Cho,
Nerima-Ku, Tokyo, Japan. (A)

Oliver, Francis A., Sound Engineer, American
Broadcasting Co. Mail: 129 S. Manhattan
PL, Los Angeles 4, Calif. (M)

Palenzuela, Carlos V., Sound Engineer, Westrex
Corp. (Asia). Mail: 418 Sta. Mesa St.,
Manila, Philippines. (A)

Petersen, Ernest L., Engineering Coordinator,
Electronics Lab., Northrop Aircraft, Inc.
Mail: 5205 Calderwood St., Long Beach 4,
Calif. (A)

Ramos, Augusto B., Technical Department
Manager, Philips Portuguesa S.A.R.L. Mail:
Rua do Telhal, 71-1 °-E., Lisbon, Portugal.
(A)

Ratcher, Mohammed E., Ill E. 26 St., New
York 10, N.Y. (A)

Roberts, Warren S., High-Speed Motion Pic-
ture Photographer, Sandia Corp. Mail:
2442 La Vetz Dr., N.E., Albuquerque, N.M.
(A)

Schock, William R., Television Engineer, KEYL,
San Antonio Television Co. Mail: 302
Freiling Dr., San Antonio 1A, Tex. (A)

Schuller, Edgar A., Motion Picture Sound Re-
cording, U.S. Army Signal Corps. Mail:
30-32 — 50 St., Woodside, L.I., N.Y. (A)

Schutz, George, Editor, Quigley Publishing Co.,
RKO Bldg., Rockefeller Center, New York
20, N.Y. (M)

362

Selzer, Robert H., University of California at
Los Angeles. Mail: 112 N. Highland Ave.,
Los Angeles 36, Calif. (S)

Sessions, Stanley H., Sound Technician, U.S.
Navy Electronics Laboratory. Mail: 1886
Maiden St., San Diego 9, Calif. (A)

Sombor, Harry, Chief Engineer, Sound Dept.,
Studio Films, Inc. Mail: 1498 Addison
Rd., Cleveland, Ohio. (M)

Speed, Richard L., TV Technician, KPIX.
Mail: 14 Ricardo La., Mill Valley, Calif.
(A)

Stainton, Walter H., Cornell University,
Goldwin Smith Hall, Ithaca, N.Y. (A)

Stevenson, Paul J., 2231 N. 12 St., Phoenix,
Ariz. (S)

Swanell, Lt. Edward F., Motion Picture Officer,
Film Editor, U.S. Air Force, 1st Photographic
Sqdn., AP&CS, 200 King St., Alexandria,
Va. (M)

Vittum, Paul W., Chemist, Research Super-
visor, Eastman Kodak Co., Kodak Park
Works, Rochester 4, N.Y. (M)

Warndorf, Lt. Col. J. P., Chief, Tech. Photo
Service Br., Support Div., Wright Air De-
velopment Center. Mail: 3817 Merrimac
Ave., Dayton 5, Ohio. (M)

Watkins, James E., Engineer, Philips Labora-
tories, Inc., 100 E. 42 St., New York 17,
N.Y. (M)

Yoshisaka, Kiyoji, Managing Director, Tokyo
Theatre Supply Co., Ltd. Mail: c/o R. A.
Haines, FEC Motion Picture Div., Special
Services Section, GHQ, Far East Com-
mand, APO 500, c/o P.M., San Francisco,
Calif. (A)

Youngman, John E., Print Foreman, Telefilms,
Inc. Mail: 4220 McFarlane Ave., Burbank,
Calif. (A)

CHANGES IN GRADE

Arnold, John, (M) to (F)
Blake, E. E., (M) to (F)
Cooke, Norman C., (S) to (A)
Dupy, Olin L., (M) to (F)
Freund, Karl, (M) to (F)
Gregory, John R., (S) to (A)
Gretener, Edgar, (M) to (F)
Hanson, W. T., Jr., (M) to (F)
Heppberger, C. E., (M) to (F)
Hood, Henry J., (M) to (F)
Ireland, R. Paul, (A) to (M)
Jensen, A. G., (M) to (F)
Landsberg, Klaus, (M) to (F)
Lawrence, C. Richmond, (S) to (A)
Perkins, Carleton S., (A) to (M)
Reichard, E. H., (M) to (F)
Robertson, A. C., (M) to (F)
Schlanger, Ben, (M) to (F)
Stott, John G., (M) to (F)
Templin, E. W., (M) to (F)
Thulin, Einar, Jr., (S) to (A)

Position Wanted

TV Producer-Director: Now Chief of Production in Army's first mobile TV system;
military experience in writing-directing high-speed, low-cost instructional productions;
formerly TV producer-director, KRON-TV San Francisco, five shows weekly; will be
separated from service Nov. 1952; desire connection in educational TV, preferably em-
ploying kinescope techniques ; married ; prefer West Coast, but willing to travel ; resume,
script samples, pictures of work — on request; 1st Lt. Robert Lownsbery, SigC Mbl TV
Sys, c/o Sig Photo Center, 35-11 35th Ave., Long Island City 1, N.Y.

Journals Available and Wanted

Available

Upon a reasonable offer to Alfred S. Norbury, 3526 Harrison St., Kansas City 3, Mo. :

Vol. 44 (Jan.-June 1945) Vol. 50 (Jan.-June 1948)

Vol. 45 (July-Dec. 1945) Vol. 51 (July-Dec. 1948)

Vol. 47 (July-Dec. 1946) Vol. 52 (Jan.-June 1949)

Vol. 48 (Jan.-June 1947) Vol. 56 (Jan.-June 1951)

Vol. 49 (July-Dec. 1947) Vol. 57 (July-Dec. 1951)

A set of Journals from January 1945 through 1951 at $15.00 plus packing and carrying
costs from Richard W. Maedler, 32-52 — 46 St., Long Island City 3, N.Y.

Complete set, in excellent condition, from January 1930 to date, plus one issue of Sep-
tember 1928 from Don Canady, 5125 Myerdale Drive, R.R. 15, Cincinnati 36, Ohio.

I Transactions Nos. 11, 14, 20, 21, 23, 25, 27, 28 and 38; and 22 years of the Journal (1930-
1951) except for Jan., Feb., Mar. and Apr. of 1934, Jan. and Apr. of 1948, and Feb. 1950;
also these extra single copies — Nov. 1930; Jan., Feb., July and Nov. 1931 ; June 1932;
Mar. and Apr. 1933; Dec. 1934; Jan. and May 1935; Oct. 1938; July and Dec. 1940;
Oct. 1948 and Jan. 1950, upon any reasonable offer made to Paul J. Larsen, Assistant to
the President, Borg- Warner Corp., 310 So. Michigan Ave., Chicago 4, 111.

Wanted

Transactions 1, 6 and 7. Contact Mrs. Dorothy Gelatt, Henry M. Lester, 101 Park Ave.,
New York 17, N.Y.

High-Speed Photography, Volume 1, reprint or original Journal, March 1949, Part II, by
John H. Waddell, Wollensak Optical Co., 850 Hudson Ave., Rochester 21, N.Y.

SMPTE Officers and Committees: The roster of Society Officers and the
Committee Chairmen and Members were published in the April Journal.

363

New Products

Aluminized mirrors specifically designed
for Schlieren observation and photography
are now available from J. A. Maurer, Inc.,

Photographic Instrumentation Div., 37-01
31st St., Long Island City 1, N.Y. The
Schlieren technique is being widely applied
to such studies as air and gas flow, aero-
dynamics, ballistics, and combustion, per-
mitting visualization and qualitative and
quantitative analysis. These mirrors,
manufactured by Optical Works Limited
of London, England, are available in a
number of standard sizes from 4 in. to
18 in. in diameter. Both spherical and
plane mirrors are included in this series,
with the spherical mirrors available in
various focal lengths. These mirrors are
manufactured to the highest practical
optical precision and are mounted in
precise mechanical mounts, permitting
coarse and fine adjustment about the
vertical and horizontal axes. Detachable
metal covers are provided to protect the
mirrors when not in use.

Meetings

American Institute of Electrical Engineers (Symposium on The Science of Music and
Its Reproduction — 1st Lecture), Nov. 7, Engineering Societies Bldg., New York,

Acoustical Society of America, Nov. 13-15, Balboa Park, San Diego, Calif.

American Standards Association, Annual Meeting, Nov. 19, Waldorf-Astoria, New York,

Society of Motion Picture and Television Engineers, Central Section Meeting (in con-
junction with I.R.E.), Nov. 21, Western Society of Engineers, Chicago, 111.
American Physical Society, Nov. 28-29, Washington University, St. Louis, Mo.
Society of Motion Picture and Television Engineers, Central Section Meeting (in con-
junction with Society of Photographic Engineers), Dec. 3, Bell & Howell Co., Chicago,

American Institute of Chemical Engineers, Annual Meeting, Dec. 7-10, Cleveland, Ohio
American Institute of Electrical Engineers (Symposium on The Science of Music and Its

Reproduction — 2d Lecture), Dec. 11, Engineering Societies Bldg., New York, N.Y.
American Institute of Electrical Engineers (Symposium on the Science of Music and Its

Reproduction — 3d Lecture), Jan. 15, Engineering Societies Bldg., New York, N.Y.
Institute of Radio Engineers Conference and Electronics Show, 5th Annual Southwestern

Conference and Show, Feb. 5-7, San Antonio, Texas
American Institute of Electrical Engineers (Symposium on the Science of Music and Its

Reproduction — 4th Lecture), Feb. 20, Engineering Societies Bldg., New York, N.Y.

364

The Economics of
High-Speed Photography

By A. C. KELLER

The economics of the use of high-speed photography in research and de-
velopment work are discussed. High-speed photography is a relatively new
tool for engineers which can be used to measure mechanical or electrical
effects or both at the same time. Examples are given which illustrate the
savings in engineering manpower as well as in materials, devices and systems.

T is A PLEASURE to accept the invitation
of your Chairman to discuss some eco-
nomic aspects of high-speed photog-
raphy. Bell Telephone Laboratories,
of which I am a member, is, as you know,
a research and development organiza-
tion and, for this reason, I will cover the
uses and the value of high-speed photog-
raphy in this area and will take my
illustrations from the communications
field.

In addressing your Society, of which
I have been a member for many years,
I would first like to have you observe
that it is a society of engineers. I would
next like you to remember what the char-
acteristics of an engineer are, particularly
in contrast to those of the scientist,
physicist, mathematician, etc. As you

Presented on October 8, 1952, as the key-
note speech for the International Sym-
posium on High-Speed Photography, at
the Society's Convention at Washington,
D.C., by A. C. Keller, Bell Telephone
Laboratories, Inc., 463 West St., New
York 14, N.Y.

know, the engineer is indeed interested,
and must be trained and informed in,
scientific matters but he has an additional
responsibility which is in his thoughts
and actions at all times. This added
characteristic of the engineer is his con-
stant concern with the economic value
of his activities. He always wants to
know, and must know, whether his proj-
ects are sound economically.

In order for the engineer to determine
the economic value of his work, he must
have suitable "tools." The tools which
an engineer uses are of many different
kinds but none are more important than
those which are used for measurement
purposes. He must be able to measure
many different things in many different
ways in order to determine the relative
economics of competing solutions of his
problems.

Almost sixty years ago, Lord Kelvin
discussed the importance of measure-
ments as follows: "When you can meas-
ure what you are speaking about, and
express it in numbers, you know some-
thing about it; but when you cannot

November 1952 Journal of the SMPTE Vol. 59

365

measure it, when you cannot express
it in numbers, your knowledge is of a
meager and unsatisfactory kind; it
may be the beginning of knowledge,
but you have scarcely, in your thoughts,
advanced to the stage of science, what-
ever the matter may be." This obser-
vation is probably more important today
than it was sixty years ago, because our
apparatus and systems have become more
and more complex and operate faster
and faster.

One of the most important of our rela-
tively new measuring tools is high-speed
photography. The use of high-speed
photography in research and develop-
ment work leading to new devices and
new systems and in understanding older
devices, is becoming increasingly im-
portant. In our own organization we
have established a regular service for
the use of engineers, which is readily
available, in the form of a variety of
good equipment and skilled people to
operate the equipment.

As measurements are taken of ap-
paratus or systems we frequently change
our ideas of how and why devices act as
they do. I can think of no other tool
available to the engineer which has
caused him to change his view of things
as much as high-speed photography.
Intuition is a valuable human trait
but it may easily lead us astray in engi-
neering matters. It has been said that
our troubles are not always due to facts
we do not know but frequently to those
things that we are sure are true but which
are in reality untrue. This applies
particularly to those things which operate
so fast that they cannot be seen or judged
by the naked eye. High-speed photog-
raphy extends our limited human
powers of observation. It not only
expands time so that we can readily see
what happens in extremely short periods
of time but it also makes possible the
quantitative measurement of these ef-
fects.

High-speed photography itself is a
broad field of activity and has been

covered in many excellent papers which
have appeared in the Journal of this
Society. However, for the application
to research and development work, it is
important to know that high-speed
photography is capable of expanding
time for mechanical or electrical effects,
or for both at the same time. It can
be used to study fast complex mechanical
motions and it can also be used to study
cathode-ray oscilloscope traces of high
speed. The ability to do these things
quantitatively has an important eco-
nomic value.

The economic value of the use of
high-speed photography comes about in
two major ways:

1 . As a saving in manhours of engineer-
ing effort by doing a job with fewer
men, or — more likely — by doing more
jobs with the same men; and

2. As savings in materials, devices or
systems either by avoiding failures
in service, by extending the useful
life of these items or by making faster
operation possible so that less equip-
ment may be used to perform the
required operations.

To illustrate these savings, some
specific examples can be cited taken
from the experiences at Bell Telephone
Laboratories in research and develop-
ment activities.

A good illustration of the savings in
engineering manpower is the case of
the development engineer working on a
new and complex mechanism. With-
out high-speed photography, it might be
necessary to build a series of mechanisms
and to test all of them for performance
and life, a very expensive proposition
both in material and in engineering
manhours. From the experience gained
with such a large variety of designs,
it would then be possible to select one
particular design for application. In
contrast, the more modern practice
of using high-speed photography en-
ables the engineer, sometimes from a
single model or parts of a model, to
determine by measurement whether

366

November 1952 Journal of the SMPTE Vol. 59

there are serious shortcomings in the
newly designed mechanism and what
the nature of the difficulties is. In
this way modifications can be made to
solve problems that may not even be
known to exist without the help of high-
speed photography. These methods
have been used with outstanding success
in many of our research and develop-
ment projects, particularly those as-
sociated with the complex electro-
mechanical mechanisms which are used
in telephone central office apparatus.

A good example of the savings in
materials, devices or systems which
result from the use of high-speed photog-
raphy is one that is present in many
mechanisms, namely, that of cam actua-
tion where continuous contact between
the cam and its follower must be had
for quiet operation, longest life and
highest operating speed. Another good
example is the telephone relay used in
switching systems. Each of these relays
has an armature operated by an elec-
tromagnet. A common problem with
relays is that of armature rebound when
a relay is released. The armature may
bounce one or more times and set up
other undesirable vibrations in the struc-
ture. In order to avoid false contact
operation, it is necessary to wait until
the effects are over before again allow-
ing the associated circuits to use the
relay. By the use of high-speed photog-
raphy, it has been possible to redesign
relay structures to minimize these vibra-
tory effects and the time for them to be
reduced to a neglibible value. Ac-
cordingly, the relay can be used by its
associated circuit more frequently in a
given length of time. In many cases
this results in fewer relays in a system to
provide necessary operating functions.

From these illustrations it can be said
that high-speed photography has made
it possible to produce economies in
materials, devices or systems by:
1. Extending the life, with corresponding
savings in the cost and the materials
of replacement units, and

2. Using fewer units to perform the
needed functions because higher oper-
ating speeds are possible without un-
due wear.

In order to illustrate the variety of
uses of high-speed photography in the
research and development area of the
communications field, a short motion
picture has been prepared. The film
has been assembled to indicate the wide
variety of uses of high-speed photog-
raphy in our work. After the showing
of the film, I will attempt to summarize
the overall economic value of high-speed
photography in the work at Bell Tele-
phone Laboratories.

(Examples were shown in a motion
picture as follows:

1. stepping switch for dial systems,

2. new wire spring relay for dial
systems,

3. crossbar switch for dial systems,

4. mercury contact switch,

5. automatic trouble recorder,

6. cam action in automatic message
accounting equipment, and

7. pushbutton telephone set.)

Let us examine the economic value of
some of the uses of high-speed photog-
raphy in the telephone apparatus field.
As you know, the Bell System designs,
manufactures and uses telephone ap-
paratus and equipment in large quanti-
ties to provide much of the nation with
telephone service. For example, one
of the scenes in the motion picture film
showed a study of the step-by-step switch
used widely in certain types of central
office dial systems. These switches fol-
low the dial pulses and perform other
essential operations in establishing a con-
nection between telephone subscribers.
Last year the Bell System manufactured
more than 600,000 switches of this type.
It is obvious that savings of even a small
amount on each of this large number of
switches would result in a substantial
sum of money. In the same way, general
purpose relays are used widely in tele-
phone switching systems, and in some
of the modern crossbar systems about

A. C. Keller: Economics of High-Speed Photography

367

five of these are used for each telephone
subscriber, so that the total number
produced each year is of the order
of five million units. Here again, small
savings, either in the cost of the relay,
its maintenance or in a reduction of the
operating time of the relay, have a high
economic value because a large number
of them are produced and used each year.

Another view of the value of high-
speed photography in Bell System re-
search and development work can be
taken from the fact that about 700 to
800 100-ft reels of high-speed motion
picture film are taken each year. Most
of these are carefully studied, frequently
by a group of engineers. From these
studies, conclusions are reached which
result in new and better understandings
of the devices and frequently design
changes or new designs are the result.
Faster processing service of the film
would be helpful in expediting develop-
ment work.

The exact dollar value of the engi-
neering manhours and materials which

have been saved by the use of high-speed
photography is difficult to evaluate but
it is obviously very large in important
research and development activities.
On one particular project of a device
made in large quantities for telephone
use, the project engineer estimated that
savings of several hundred thousand
dollars a year had resulted. Other proj-
ects have saved much less and some have
shown even larger savings.

In closing, I would like to say that
there are many other economic advan-
tages in the use of high-speed photog-
raphy in maintenance problems, training
problems, etc., which I have not touched
upon in outlining the engineering value of
this tool in research and development
work. Our daily use of high-speed
photography, leads us to expect an ex-
panding application of this new and im-
portant engineering tool and as a result
will make better use of that most pre-
cious commodity — engineering man-
power.

368

November 1952 Journal of the SMPTE Vol. 59

Transient Pressure Recording with a High-
Speed Interferometer Camera

By WILLARD E. BUCK

This paper describes a transient-pressure recording camera with a full scale
pressure range (by changing diaphragms) of 3 psi to 50,000 psi, and an ac-
curacy of one-half per cent of full scale for any range. Its stability and hys-
teresis are such that a single static calibration suffices for years of dynamic
measurements, and its frequency response varies from 10,000 cycle/sec to
100,000 cycle/sec, depending on the pressure range of the diaphragm used.
The paper includes records of interesting applications.

IONVENTIONAL PRESSURE gauges which
have high frequency responses are built
as follows: A pressure-sensitive device
with the required natural frequency
(usually a diaphragm or a form of
Bourdon tube which has a minute dis-
placement or rotation proportional to
pressure applied) is the heart of the
instrument. This small rotation or dis-
placement is converted into an electrical
response by an electromechanical trans-
ducer of the designer's choice, usually
either a variable condenser or variable
reluctance device. The small electrical
impulse thus obtained is amplified and
recorded without losing the charac-
teristics of the original signal.

For frequency responses above about
2000 cycle/sec, the most convenient
presentation is on a cathode-ray screen.
However, if these fleeting signals are to

Presented on October 10, 1952, at the
Society's Convention at Washington,
D. C., by Willard E. Buck, University of
California Los Alamos Scientific Labora-
tory, P. O. Box 1663, Los Alamos, N.M.

be studied, they must be recorded on
photographic film; and further, if the
event lasts longer than a very small
fraction of a second a continuous moving
film camera is usually required.

It is obvious that recording the move-
ment of a diaphragm directly on the
photographic film is highly desirable if
the system is sufficiently sensitive and has
the required frequency response. Such
a system exists in the familiar form of
interference fringes which can be re-
corded directly with a moving film
camera.

The unique properties which make
this system an ideal amplifier are worth
further discussion. The amplification
factor, defined as the ratio of distance
moved by the center of the diaphragm
to the corresponding change in fringe
diameter, is 14,620 for a fringe pattern
using the 5461 A line of mercury and
having a distance between light maxima
of 2 mm. The frequency response of
such an amplifier is approximately half
the frequency of the light used. In
this example it would be approximately

November 1952 Journal of the SMPTE Vol. 59

369

QUAKTZ PLATE

Fig. 1. Schematic of optical system used on interferometer gauge.

2.7 X 1014 cycle/sec. The gain of this
amplifier is as constant as the wavelength
of light. This, of course, is as good as
any quantity we know of and is actually
used as the fundamental standard of
length measurement.

With such a satisfactory amplifier the
characteristics of a pressure measuring
device depend entirely on the me-
chanics of the diaphragm and the re-
cording system used.

A photographic and optical system
designed to use such an amplifier was
first described in October 1948,1-2 but
is briefly described here again to clarify
the remainder of this paper for those
who are not familiar with the inter-
ferometer gauge.

Optical System

In Fig. 1, a steel diaphragm is re-
ceiving a transient pressure as repre-
sented by the hammer blow. The
diaphragm deflects slightly in response
to the pressure, and it is this slight de-
flection that we wish to record on the
moving film. To do this a quartz
backing plate, with one face ground and
polished spherically concave on a large
radius, is placed next to the flat side of
the diaphragm. The outer edges of
the plate are ground and polished flat

to make a highly stable reference with
respect to the steel diaphragm.

The spherical cavity in the quartz
is coated with a half-reflecting film of
aluminum so that when the assembly is
viewed in monochromatic light a set
of sharply defined interference fringes,
or Newton's rings, is formed. If the
monochromatic light is admitted through
a glass prism as shown in the diagram,
however, only a narrow strip of this set
of rings is formed. The rings then ap-
pear as short sections of arcs and may
be photographed on a moving film as
distinct parallel lines. Any movement
of the diaphragm, however, causes a
change in the air space between the
quartz plate and the steel, which makes
an amplified movement at the sections
of arc and a corresponding change in the
lines recorded on the moving film.

In practice, the quartz backing piece
is ground to produce approximately 50
fringes. Since a deflection of about
one-tenth of a fringe can be measured
on the film, the displacement of the dia-
phragm can be measured to about one
part in 500.

As long as the deflection of the dia-
phragm stays well below the elastic
limit of the steel or quartz used, it is
strictly proportional to the pressure
applied. The number of fringes from

370

November 1952 Journal of the SMPTE Vol. 59

Fig. 2. Cutaway of first self-contained model of interferometer gauge.

the outer ring, which is in contact with
the diaphragm, to the center of the
diaphragm is directly proportional to the
distance from the center of the dia-
phragm to the quartz backing plate;
therefore, the number of fringes counted
on a photographic film is directly pro-
portional to the pressure applied. This
linear relationship is, of course, a highly
desirable feature for ease of calibration
and interpretation of records.

Camera Details

The camera proper is of the familiar
continuous moving film variety, but
the special features of various models
which have been developed should be
mentioned.

The general scheme for film transport
is the same on all models, and consists
of a high-speed motor directly coupled
to the take-up spool. The speed of the

motor is controlled by a governor which
is mounted on an idler drum driven
by the friction of the film being pulled
over it. Thus the motor speed is
varied to give a constant film speed as
the take-up reel increases in size. On
most models the film speed can be con-
trolled from 10 to 80 ft/sec. The sup-
ply spool has an adjustable drag to keep
tension on the film which supplies driving
power for the governor and to keep the
film in the image plane. One model
which was intended for short runs has a
magnetic fluid brake3 on the take-up reel
which is supplied with power as soon
as the driving motor circuit is broken.
This camera will make as many as ten
runs on a 100-ft spool of film at 80
ft/sec, and have the major part of each
run at full speed.

One model is equipped with a footage
counter which reveals the amount of

W. E. Buck: Pressure Recording With Interferometer Camera

371

film left in the camera, and has a dial
which can be set for the required film
length in the next run.

Figure 2 is a cutaway drawing of the
first self-contained interferometer gauge
ever built. It was designed to measure
the internal pressure of rocket motors
in the range of 0 to 2000 psi. To keep
the hot gases of the rocket motor from
destroying the diaphragm, the pressure
is conducted to the diaphragm by a
short oil line. By choosing the proper
viscosity of oil and the proper size of
line, the diaphragm can be critically
damped. The oil line then acts as a
low-pass filter so that the frequency re-
sponse of the system is the frequency
response of the oil line itself. By keeping
the line short and making sure there is
no air in the system, the frequency re-
sponse can be held above 10,000 cycle/
sec. In the lower left corner of Fig. 2
is a blower fan used to keep the light
cool. This is necessary because ap-
proximately 100 w of power must be
consumed to get a sufficiently bright
source. Between the two film spools
is a slotted disc which is driven by a
synchronous motor and puts timing
marks on the edge of the film by inter-
rupting the main light beam. The slots
in this drum are of varying depths giving
5, 10 and 20 millisecond marks with
increased lengths of line in each case
to assist in analyzing the film.

In the center of the camera and next
to the film frame is a holder for a small
cylindrical lens. This lens is not shown
in the optical diagram (Fig. 1) as it is
not an essential component, but it does
serve to reduce the size of the image of
the slot on the film, thus increasing the
frequency response that can be read for
any given film speed. Mounted with
its roller on the take-up spool is a micro-
switch which is operated by the increas-
ing diameter of the take-up spool. This
switch interrupts the current to the drive
motor and applies energy to the brake
on the supply spool.

Figure 3 is a picture of a model that
was intended primarily for measuring
pressures in blast waves, although it has
proven to be a versatile camera and has
been put to many other uses. The plate
marked "Mounting for Quartz Dia-
phragm" is mounted flush with the
surface over which the shock wave
travels. This may be either the inside
of the shock tube or the surface of the
ground, as the experiment requires.
The main features of this design are its
ease of construction and its ruggedness.
It is, of course, designed to stand the
jars that it will receive when measuring
shock waves. As in all very high speed
cameras, there is a problem in keeping
the end of the film intact as the driving
motor comes to a stop. If the film is
allowed to run free, approximately 1 in.
is snapped off on every revolution, and
at approximately 10,000 rpm, an ap-
preciable section of the film can be
destroyed in a very short time. To
prevent this loss of record, two pre-
cautions have been taken. One is the
microswitch which cuts off the power
when the reel gets full, and the second
is the two spring leaves which can be seen
on either side of the take-up spool.
These leaves are mounted so that, as
the spool gets full, the film bears against
the springs and acts as a brake to bring
the motor to a stop in a very short
time. With these two precautionary
measures in operation the film can be
used to within a few feet of the end of
the spool without fear of losing a record.

Figure 4 shows the latest 16mm camera
design. It is intended to measure pres-
sures in free air or anywhere else that
a small size is important. The camera
model shown in Figs. 2 and 3 has self-
contained power supplies and needs
only to be supplied with 110 v a-c and a
starting signal. However, this latest
camera requires an external power
supply as well as a starting signal. As
can be seen from the picture, the case
is extremely rugged and will stand
pressures of 100-lb shock without being

372

November 1952 Journal of the SMPTE Vol. 59

MOUNTING FOR QUARTZ

DIAPHRAGM

MING LIGHT

CYLINDRSCAL
LENS

MICRO SWITCH

FILM SPOOLS

Fig. 3. Interior of model designed for blast-pressure measurements.

Fig. 4. Compact 16mm interferometer gauge.
W. E. Buck: Pressure Recording With Interferometer Camera 373

DAMPING FLUID

Fig. 5. Drawing of quartz diaphragm and damping assembly.

damaged. The diaphragm assembly
shown in the extreme left is easily de-
tachable, and diaphragms varying in
range from 3 psi to 50,000 psi can be
quickly substituted. This makes a single
instrument that can record the pressure
wave from a hand clap as well as the
internal pressures of our largest rifles.

Diaphragm Construction

For pressures in the range of 3 to 100
psi it is possible and desirable to use a
quartz diaphragm instead of the steel
diaphragm shown in Fig. 1. Figure 5
is a drawing of this diaphragm assembly.

Fused quartz is an almost ideal ma-
terial for a pressure diaphragm. Its
ratio of Young's modulus to density
is high, thus allowing a high natural
frequency for a given pressure range.
Fused quartz also has one of the smallest
temperature coefficients known, and
consequently its calibration is almost
independent of temperature. The most
interesting feature of the quartz dia-
phragm, however, is its ability to be
optically contacted with another piece
of fused quartz. This property allows
us to build a diaphragm and a backing
plate optically contacted together to form
a single integral unit. This system is
so stable that it requires only one careful
static calibration for the life of the
instrument.

To sum up the features of this as-
sembly, we have the following charac-
teristics :

1. High frequency response for a
given pressure range.

2. A negligibly small temperature
coefficient.

3. A stability that permits a single
calibration for the life of the gauge.

4. No detectable hysteresis.

Damping

This quartz diaphragm, with almost
perfect elastic properties, will vibrate
at its natural frequency for a long time
when subjected to a shock wave if not
properly damped. One of the most
difficult problems in the design of this
instrument was to find the proper
damping method for the quartz dia-
phragm. All sorts of schemes were
tried, but all systems that gave adequate
damping loaded a diaphragm so much
that they reduced its natural frequency
two or three times. This, of course, was
highly undesirable, as one of the main
features of the gauge is its high frequency
response. Finally, almost by accident,
it was found that if the direction of
motion of the damping fluid was at
right angles to that of the diaphragm,
the mass of the damper did not add to
the mass of the diaphragm and hence
the frequency response was not de-
stroyed. To accomplish this damping
it was only necessary to bring a rigid
metal support close to the front surface
of the diaphragm in such a way that a
drop of the proper viscosity fluid could

374

November 1952 Journal of the SMPTE Vol. 59

.-» .s .6

TIME IN MILLISECONDS

Fig. 6. Enlargement of an original record and method of plotting
pressure-time curve.

be placed between the diaphragm and
the metal support.

As the diaphragm deflects, the oil
must flow along the face of the dia-
phragm to accommodate the change in
volume between the diaphragm and the
metal support. Damping is caused by
the viscosity of the oil. Decreasing the
clearance between the support and the
diaphragm will increase the velocity of
the oil and hence its damping action.
A 0.040-in. diaphragm with a pressure
range of 0 to 70 psi is critically damped
if a 1000-centistoke oil drop is used
with a clearance of about 0.004 in.

Figure 5 also shows the diaphragm
damper and filter unit combination.
The damping fluid is held in place
between the metal plate and the dia-
phragm by its surface tension. After
several months of field use, diaphragms
have been inspected, and the oil drops
have been found to be intact and damp-
ing properly.

As these gauges are intended for field
use of the most exacting kind, it was
found necessary to put a water and dust
filter over the diaphragm proper. The
material used for this filter has the trade
name "Porex." It is manufactured by

W. E. Buck: Pressure Recording With Interferometer Camera

375

Chorge: 22.62 # Comp B
Distance 24 ft
Scale I fringe =! 67PSI
Shape cylindrical

Fig. 7. Blast-pressure curve of small charge showing
three separate shocks arriving at gauge.

22840^

*«

•-^Q

? °*

*- — ,

-o^.

•o-

;

(

Time in Milliseconds

Fig. 8. Pressure-time plot of internal pressure developed
by a typical large-caliber rifle.

Moraine Products Division of General
Motors Corp. "Porex" is made of a
large number of small beads which are
bonded on their outer edges by heat
and pressure until the whole unit is
quite rigid but leaving a fair percentage
of air passage between the balls. The
"Porex" after manufacture is dipped
into hot paraffin and the excess paraffin
blown out with compressed air. This
leaves each individual ball coated with
a very thin layer of paraffin which will
not be wet with water droplets. A
"Porex" filter thus treated will not pass
water even though it is immersed one-
quarter inch or so. A blast gauge thus

protected can be left out in the dust
and rain even though its sensitive
diaphragm is turned up flush with the
ground. By keeping the volume of air
small and the area of the "Porex" disc
large, the flow time is so rapid that it
does not measurably decrease the fre-
quency response of the diaphragm.

Records

It is difficult to find a practical record
that can be displayed on a magazine
page, as most events of interest are a
number of milliseconds long and would
require many feet of paper to present
them adequately. The record of Fig. 6

376

November 1952 Journal of the SMPTE Vol. 59

was chosen because the whole event
could be shown on a single sheet of
paper. This figure not only shows an
enlargement of the original record, and
the graph of pressure vs. time obtained
from it, but also shows the method of
plotting this curve. The record is of
a small-volume hydraulic reservoir that
is carefully filled with oil to exclude all
gas pockets. The pressure is raised to
1000 psi as read on a dead -weight tester,
and a quick-acting valve then releases
the pressure to atmospheric.

The most satisfactory way of reducing
the data of the film to a curve is to have
a two-man team. An experienced man
can read points off the film as fast as
his partner can plot them on a piece of
graph paper. With this system an
average curve can be plotted in ap-
proximately 15 min. This type of rapid
plotting allows one to achieve an ac-
curacy of within about 0.5%. If higher-
accuracy plots are desired, a more
elaborate technique must be employed
requiring some careful measurements of
the fringe spacing. The accuracy ob-
tainable by this gauge is not a function
of the mechanics of the diaphragm but
is determined by the accuracy of the
original calibration and the accuracy
with which the film can be read. To
date we have never had an application
in which the highest possible accuracy
was required. We, therefore, have
no data on what ultimately might be
obtained.

Figure 7 is a blast-pressure curve
taken with the gauge shown in Fig. 3.
This shot was taken on an asphalt apron
that was level and dust-free. The
diaphragm of the gauge was mounted
flush with the surface of the apron and
at a 24-ft air-line distance from the
explosive. The explosive was a 22.6-lb
cylinder of Composition B suspended in
the air by a small string and having its
cylindrical axis at right angles to the
line of measurement. It was detonated
simultaneously in the center of each end
of the cylinder. The record shows

clearly three separate shocks arriving
at the gauge. These shocks are prob-
ably due to the interreaction of wave
fronts from the cylindrical and flat
sections of the charge, respectively. The
secondary shock fronts arc a function of
the orientation of the cylindrical charge
as well as the distance of the gauge from
the point of explosion.

Figure 8 is the first part of a pressure-
time plot of the internal pressure de-
veloped by a large rifle such as the
Navy uses on shipboard. This record
is presented to emphasize two points:
one, the extremely high pressures which
the gauge is capable of measuring
accurately; and two, to show how easily
the gauge handles the time resolution
of events that we normally think of as
being very rapid.

Reference

1. W. E. Buck and W. H. Barkas, "Dy-
namic pressure measurement by optical
interference," Rev. Sci. Instr., 19:
678-684, Oct. 1948.

2. W. H. Barkas and W. E. Buck, "Inter-
ferometer gauge," U.S. Patent Office,
No. 2,591,666, Apr. 8, 1952.

3. Robert C. Mack, "Magnetic fluid
clutch of unique design," Automotive
Ind., 98: 38, 1948.

Discussion

Morton Sultanoff (Terminal Ballistics
Laboratory, Aberdeen Proving Ground, Md.}:
By the appearance of the gauge, I would
assume you are measuring the reaction of
gauge material to the shock. How do you
correct back to the actual shock from the
response of the gauge material?

Dr. Buck: The quartz diaphragm
actually responds to the shock profile
within the limitations of its frequency
response which is 10,000 to 100,000 cycles
per second depending upon the pressure
range used. The diaphragm does not,
however, follow the shock exactly, as the
shock pressure rises in much less than one
hundred thousandths of a second. A
pressure-time curve plotted with points
every tenth of a millisecond would not see
an error between actual and measured
values, but if these points were plotted

W. E. Buck: Pressure Recording With Interferometer Camera

377

at one hundredth of this spacing, a definite
discrepancy at the shock front would be
evident.

Kurt Stehling (Bell Aircraft): The ques-
tion I have is your application to rocket
motors. Do you use a microdensitometer?
If so, you have several miles of film. The
second question I have is, did you say the
quartz is semialuminized on its surface?

Dr. Buck: Yes. If the quartz is not
semialuminized, the fringes are very
difficult to photograph, but if it is alumi-
nized to the proper reflectance, the con-
trast between light and dark fringes is
high, so that it is very easy to photograph.

In answer to your first question. I have
not had an application where the accuracy
required warranted the use of a micro-
densitometer. Reading quickly by eye
an accuracy of 0.5 per cent is easily
obtained. By using a microdensitometer
the reading accuracy could probably be
pushed well beyond this point.

Mr. Stehling: I was not thinking so
much of the accuracy as the ability to
take this data and feed it to a computer
or card system, an IBM system.

Dr. Buck: We have not tried to use a
card system as points can be read from the
film about as rapidly as they can be copied
down. A normal shock wave curve such
as shown in this paper takes about 15
minutes to plot.

Amy E. Griffin (U.S. Naval Ordnance Test
Station, China Lake, Calif.): I would like
to make a comment that there are quite
a few machines that have been developed
in the last few years for analyzing records
of this type, in which you have a motor
control to transport film over to a certain
position so that the operator can get the
image by feeding a film — it can be fed
automatically into a computer at the same
time for further computations.

Kenneth Morgan (Interchemical Corp.): I
do not quite understand how you obtained
the original calibration so that you know
what distance corresponds to what pressure.

Dr. Buck: We had a great deal of diffi-
culty proving that a static calibration was
equivalent to a dynamic one; however,
through numerous tests such as comparing
a static calibration to the peak pressure in
a shock wave as measured by velocity
gauges, we have gradually accumulated
enough data to convince almost anyone.
Once you have established the equivalence
of a static and dynamic calibration it is
simple to get as accurate a static calibration
as required. The pressure element is
clamped onto a pressure chamber and
subjected to various pressures as measured
by a dead weight tester. A short section
of film is run for each pressure and a curve
of pressure against fringe change plotted.

378

November 1952 Journal of the SMPTE Vol. 59

Optimum Slit Height in Photo-
graphic Sound-Track Reproducers

By W. K. GRIMWOOD and J. R. HORAK

For a specified reproducer frequency-response characteristic, there exists
an optimum slit height. The optimum slit height depends upon the relative
amounts of shot noise from the photosurface and thermal noise from the
amplifier circuits. Calculated and measured values of optimum slit height
are presented. The slit height which minimizes noise is undesirably large.
Shot and thermal noise levels may be ignored if the d-c voltage drop across
the effective phototube load resistor, without film in the light path, is of the
order of 300 mv or higher.

HE TERM "optimum" when applied
to the height of the scanning slit in a
photographic sound-track reproducer can
be variously interpreted. One inter-
pretation appearing in the literature of
the subject is the slit height which gives
maximum signal output at an assigned
frequency,1 another is that slit height
which results in maximum ratio of signal-
to-phototube noise at an assigned fre-
quency.2 The definition of "optimum"
taken as the basis for this paper is that
value of slit height which gives maximum
signal-to-system noise ratio for a speci-
fied frequency-response characteristic
as measured from film modulation to
amplifier output. Film noise plays no

Communication No. 1514 from the Kodak
Research Laboratories, by W. K. Grim-
wood and J. R. Horak, Kodak Research
Laboratories, Eastman Kodak Co., Roch-
ester 4, N.Y., presented by J. R. Horak
on October 10, 1952, at the Society's
Convention at Washington, D.C.

part in the determination of optimum
slit height. The effective size of the
scanning beam is determined, not by the
optical slit image, but by the overall
response of the system. Since the re-
producer frequency-response charac-
teristic is fixed, the effective slit height is
fixed. The reasonable assumptions are
made that all phototube noise is shot
noise and that all amplifier noise is
thermal noise arising in the input cou-
pling circuit. Both sources of noise have,
therefore, the spectral distribution of
"white noise" before any frequency dis-
crimination is encountered.

The reproducer frequency-response
on which are based the calculated and
experimental data in this paper is one
of the Standard Electrical Characteris-
tics for Theater Sound Systems3 specified
by the Motion Picture Research Council
(Fig. 1). The same set of curves have
been proposed as standards for 16mm
review rooms.4

November 1952 Journal of the SMPTE Vol. 59

379

Since the Standard Electrical Charac-
teristics do not extend higher than 8000
cycles/sec, this frequency has been taken
as the cutoff frequency for convenience
in expressing slit height as a ratio to the
cutoff wavelength, Xc. Because the
electrical response cannot suddenly cease
at 8000 cycles/sec, the equalizer curves of
Fig. 2 have been carried beyond this fre-
quency at a rate of loss which appears
reasonable and practical. High-fre-
quency discrimination by electro-acous-
tic and acoustic elements has not been
included in the calculations. These
factors, when known, can readily be
taken into account. Their inclusion will

-20

50 100 500 IK 5K

Frequency in cycles per second

Fig. 1 Standard Electrical
Characteristic.

IOK

theoretically shift the optimum slit
height slightly in the direction of higher
slits. Likewise no attempt has been
made to include subjective factors which
might weight the noise spectrum.

Theoretical Optimum Slit Height

Consider a sound reproducer consist-
ing of an optical system which projects
on the film plane a sharply defined,
uniformly illuminated scanning beam.
The scanning beam impinges upon a film
which has constant average transmit-
tance and a percentage modulation
which does not vary with wavelength.
The light transmitted by the film falls
upon a phototube which is coupled
to an amplifier. The amplifier is con-
sidered to be so designed that constant
percentage light modulation produces
an output level, the frequency depend-
ence of which is specified by Fig. 1.
If the height of the scanning beam, h,
is changed, the average light level upon
the phototube and the average photo-
tube current will change proportion-
ately. The shot-noise power generated
in the phototube is proportional to the
phototube current. Thermal-noise
power, arising in the coupling circuit,
is constant per cycle of bandwidth for a
c — ' temperature.5-6 For frequencies

fixed

-30

100 500 IK

Frequency in cycles per second

Curve

1 0.133

2 0.318

3 0.477

4 0.634

5 0.823

6 0 . 938
1.111

h = slit height,
Xc = wavelength at 8000
cycles/sec.

5K IOK

Fig. 2. Equalization required to match Standard Electrical Characteristic.

380

November 1952 Journal of the SMPTE Vol. 59

4
j/>

I 2

-2

-4

tr -6

-8

-10

.6
h/Xc

1.0

Fig. 3. Shot-noise power vs. h/\c.

where the height of the scanning beam
is small compared to the wavelength of
the film modulation, the signal ampli-
tude will be proportional to the scanning-
beam height. Thus, in this frequency
range, the ratio of signal amplitude to
shot-noise amplitude will be propor-
tional to the square root of the slit height.
The ratio of signal amplitude to thermal
noise will be directly proportional to
the slit height.

At frequencies where the slit height
is an appreciable fraction of the modula-
tion wavelength, the signal amplitude
will also be a function of frequency.7
Since the overall frequency response has
been specified, the product of the fre-
quency discrimination due to the slit
height and the frequency discrimination
due to amplifier compensating equalizers
must remain fixed. The necessary am-
plifier-frequency characteristics, plotted
with decibel ordinates, are shown in
Fig. 2. These equalizer characteristics
distort the frequency spectra of shot and
thermal noises. Because of the fre-

I 2

•o

.E_4

- 6

w
o
c -8

-12

-14

1.0

.6
h/Xc

Fig. 4. Thermal-noise power vs.

quency characteristics of the amplifier
equalizers, both noise levels will be func-
tions of slit height. The rms noise
voltage must be determined by integra-
tion of noise power per cycle over the
frequency band of the amplifier. This
may be done graphically by plotting the
equalizer characteristics as the ampli-
tude squared versus the frequency, meas-
uring the areas under these curves and
taking the square roots of the areas.
Each such calculation gives the noise
voltage, either shot or thermal, asso-
ciated with a particular ratio of slit
height to wavelength. Signal-to-noise
ratios versus slit height-to-wavelength
ratio can now be plotted. Figure 3
is a plot of shot noise in decibels versus
the ratio of slit height to wavelength
at cutoff. Figure 4 is a similar curve
for thermal noise. In both figures, the
noise levels are referred to an arbitrary
fixed signal level at the amplifier output.
Minimum noise level occurs at slightly
different h/\c ratios on the two curves
of Figs. 3 and 4. The minimum

Grimwood and Horak: Reproducer Slit Height

381

2
Ratio of

46 8 10 12

shot noise power per cycle
thermal noise power per cycle

Fig. 5. Optimum h/\c vs. noise-power
ratio.

total noise must be at an h/\c
ratio between these two minima. The
optimum slit height will thus be a
function of the ratio of shot noise to
thermal noise. The individual noise
components can be added vectorially
for various assumed ratios of shot noise
to thermal noise, and the total noise
plotted against h/\c, with noise ratios as
a parameter. The locus of the minimum
of this family of curves may then be
plotted as optimum h/\c versus the ratio
of shot noise to thermal noise, as in
Fig. 5.

It has been shown5-8 that shot noise
and thermal noise are equal when the
product of the average phototube current
by the effective* phototube load resist-
ance is 50 mv. This relation may be
used to plot shot noise-to-thermal noise
ratio versus the average voltage across
the phototube load. Combining this

* Whereas the d-c voltage is developed
across the phototube anode resistor, the
noise components appear across the effec-
tive a-c load impedance in the anode
circuit.

information with the data of Fig. 5
results in the curve of Fig. 6 in which
optimum h/\c ratio is related to milli-
volts drop across the phototube load
resistance.

The preceding relations apply when
the phototube is a simple vacuum type.
The results are modified in two respects
when gas phototubes are used. The
high-frequency discrimination of gas
phototubes modifies the spectral distri-
bution of the phototube shot noise rela-
tive to the spectral distribution of the
amplifier thermal noise since the fre-
quency discrimination arises in the photo-
tube prior to the source of the thermal
noise. Calculations have been made
taking this factor into account, with the
result that the effect of gas-phototube
frequency discrimination is one of negli-
gible magnitude in the determination
of optimum slit height. The second
effect of a gas phototube is to multiply
the ratio of shot noise to thermal noise
by the gas amplification factor. Thus,
the millivolt scale of Fig. 6 must be divided
by the gas amplification factor when this
curve is applied to gas phototubes. This
same effect would apply were a photo-
multiplier tube to be used for sound re-
production. The obvious practical ef-
fect of using a photomultiplier tube
would be the elimination of thermal
noise, so that only the curve of Fig. 3
would be pertinent.

Measured Optimum Slit Height

Measured data were taken using a
16mm sound-film reproducer designed
some years ago by J. G. Streiffert, of
these Laboratories. This machine is
well adapted to measurements with
various slit heights by virtue of its double-
slit optical system with a series of inter-
changeable secondary slits. An 8.5-v,
4.0-amp lamp and conventional sound-
reproducer optical system are used to
form a slit image, approximately 1.2
mils in height, at the film plane. The
slit image at the film plane is enlarged
6.5 times by a microscope objective and

382

November 1952 Journal of the SMPTE Vol. 59

.84F

.70

O.I 0.5 1.0 5.0 10 50 100 5001000

Millivolt D.C. drop across effective PEC. load resistance

Fig. 6. Optimum h/\c vs. coupling resistance voltage drop.

imaged onto a secondary slit. A motor-
driven chopper is inserted in the light
path between the microscope objective
and the secondary slit to provide a ref-
erence signal level for calibration pur-
poses. The chopping frequency is ap-
proximately 200 cycles/sec. Radiation
passed by the second slit is collected by
a lens which images the objective lens
onto the phototube surface. The photo-
tube is a Type 927 (S-l surface) operated
at 52 v. This subnormal anode voltage
is used because frequency discrimination
due to the gas-amplification factor was
found to be negligible at this voltage
level. The phototube load resistor of
2 megohms is also the grid resistor of the
amplifier. The amplifier is followed by
a series of filters and a vacuum tube
voltmeter. For each of the seven avail-
able secondary slits, the amplifier was
separately equalized by an adjustable
equalizer in the feedback path so that
the overall response, as measured at the
voltmeter position by means of a cali-
brated frequency test film, approximated
the response curve of Fig. 1 . The maxi-
mum spread between the seven response
curves is 0.7 db from 50 to 7000 cycles/sec,
increasing to 2.1 db at 8000 cycles/sec.
The maximum deviation between the
group of seven measured responses and
the standard curve of Fig. 1 is within

the limits of +0.8 db and -0.4 db from
50 to 7000 cycles/sec. Above 7000
cycles/sec, the measured responses drop
more rapidly than the design objective;
at 8000 cycles/sec, the extreme devia-
tion is —6.1 db. Above 8000 cycles/sec,
the electrical response drops very rapidly
so that, in spite of the equalizing re-
quired for the largest slit, the noise com-
ponents above 9000 cycles/sec are negli-
gible. All noise measurements are made
with a 500-cycle/sec high-pass filter
in order to remove any hum components
present. This filter is removed when
measuring signal levels. The noise
level with the amplifier input shorted is
20 db below the noise level with the
normal input condition. This measure-
ment is for a 200-cycle/sec bandwidth
centered at 8000 cycles/sec; at lower
frequencies, the noise with a shorted
input is a few decibels lower.

The theoretical noise versus slit height
curves are based upon the assumption
that the slit is perfect, that is, the bound-
aries are sharply defined and the illu-
mination is perfectly uniform over the
entire image area. Since, in practice,
this condition is rarely satisfied, it is
necessary to define an "equivalent slit
height." Equivalent slit height is that
value of slit height determined by
matching a measured amplitude-wave-

Grimwood and Horak: Reproducer Slit Height

383

Table I. Slit Image Heights and Relative illuminance Data

Relative illuminance in db

Slit height at film plane Measured

Calculated Equivalent Theoretical (avg.)

Correction factors in db

Signal level Shot

thermal noise noise

0.127

0.290

0.300

7.47

7.82

-0.35

-0.18

0.447

0.432

10.63

12.77

-2.14

-1.07

0.605

0.490

11.73

15.18

-3.45

-1.73

0.861

0.600

13.48

16.10

-2.62

-1.31

1.047

0.735

15.26

18.25

-2.99

-1.50

1.180

0.870

16.72

18.80

-2.08

-1.04

length curve with the theoretical ampli-
tude-wavelength curve of a perfect slit.
The values of slit heights which are used
here in plotting measured noise levels
have been determined by this technique.
The precision of determining slit height
from slit-loss data becomes rather poor
for very small slit heights, since it was
not practical to make measurements at
wavelengths of much less than 1 mil.
However, measurements of the light
distribution along the height of the image
of the primary slit show that the uni-
formity is very good for the smaller
values of secondary slit height when the
secondary slits are properly aligned with
respect to the primary slit image. At
the smaller slit sizes, the equivalent slit
height approaches the value deter-
mined by dividing the measured height
of the physical secondary slit by the
magnification. For the smallest value
of secondary slit, this calculated value
is used since it is corroborated by the
equivalent slit-height data.

The theoretical curves are also com-
puted on the assumption that the illu-
minance upon the phototube is pro-
portional to the slit height. Measure-
ments show that this assumption is not,
in this instance, justified. Although the
data are consistent within each slit
height, there are inconsistencies between
the series of data for the several slits
due to factors such as the necessary
realignment of optics when changing
slits, adjustments of lamp position for
minimum microphonics, etc. From the

relative illuminance data for the several
slits, appropriate correction factors are
determined which are applied to all
signal and noise level data. Table I
gives the slit image heights, relative il-
luminance data, and the correction
factors.

For each of the seven slits, a series of
measurements were taken of signal levels
for both chopped light and calibrated
film, film noise level, phototube noise
level, and amplifier noise level. Non-
diffusing neutral densities placed in the
light beam ahead of the phototube were
used to control the ratio of phototube
noise to amplifier noise. The illumi-
nance at the phototube, with the smallest
slit in place and no density or film in the
light path, was such that phototube noise
was 7 db above thermal noise. Since
the total noise level and the thermal
noise level were known, the phototube
noise level could be calculated. The
correction factors of Table I were applied
to these data, and all measurements were
adjusted to a common signal reference
level. The slit sizes are expressed as
ratios of slit height to the wavelength
corresponding to a cutoff frequency of
8000 cycles/sec.

The results are shown by the curves
of Fig. 7. Curve A is the theoretical
relation between shot noise and slit
height taken from Fig. 3. The crosses
are experimental points. Similarly,
Curve B is the theoretical thermal noise
versus slit-height relation of Fig. 4, the
squares representing experimental data.

384

November 1952 Journal of the SMPTE Vol. 59

Curve C gives the relation between film
noise level and slit height (signal level
held constant) with measured values
indicated by the circles. Note that the
location of these curves on the ordinate
scale has no significance. The absolute-
levels depend upon such factors as il-
luminance level, phototube sensitivity,
phototube load resistance, film density,
and film granularity. Accordingly, the
experimental curves have been adjusted
on the ordinate scale for best fit with the
theoretical curves. A further check of
the theoretical results may be obtained
by making use of the relation between
the phototube d-c output voltage and
the ratio of shot noise to thermal noise.
The measured gas-amplification factor
(anode volts = 52) is 2.3, so that unity
noise ratio should be obtained when the
d-c voltage drop across the phototube
effective load is 22.5 mv. The measured
value is 23.8 mv.

Discussion of Results

The optimum slit height for minimum
electrical noise level is, from Fig. 7,
some value of h/\c between 0.71 (mini-
mum phototube noise) and 0.81 (mini-
mum amplifier noise). Using the former
value gives an electrical noise level not
more than 0.4 db higher than the true
optimum. An h/\c value of 0.71 gives
actual slit heights of 0.64 mils and 1.60
mils for sound-reproducer speeds of
7.2 in. /sec and 18 in. /sec, respectively.
The corresponding slit loss at a frequency
of 8000 cycles/sec is 8.9 db. A slit loss
of this magnitude is undesirable, partly
because of the required equalizing, but
chiefly because relatively small differ-
ences between actual slit heights and
design value will cause appreciable
changes in overall frequency response.
If phototube noise is much greater than
amplifier noise, there is considerable
tolerance in the choice of slit height.
Then h/\c may have values from 0.44
(at which value the slit loss is but 3 db)
to 0.9 without increasing the noise level
by more than 1 db.

1-4

6-8

-12

-14

6. Amplifier noise
I I I

.6
h/X,

8 1,0

Fig. 7. Relative noise power vs. h/\c:

- = Theoretical curves;
O, D, X = Experimental points;
Curves adjusted to 0 db at h/\c = 0.133.

Because phototube noise voltage is
proportional to the square root of illu-
minance, the most adverse conditions,
with respect to the ratio of phototube
noise to amplifier noise, exist when noise-
reduction sound tracks are used. The
illuminance on the phototube during a
silent portion of a noise-reduction track
may be only about 5% of the illuminance
with no film in the reproducer. Assum-
ing the phototube to have a gas-ampli-
fication factor of 6 and no film in the
light path, the d-c level across the ef-
fective phototube load resistor must be
about 300 mv (this is equivalent to 106
rms mv for 100% light modulation, as by
a sinusoidal light chopper) for phototube-
noise power to be double the amplifier-
noise power when a fully biased noise-
reduction sound track is reproduced.

Grimwood and Horak: Reproducer Slit Height

385

Under these conditions, the amplifier
will still contribute about 2 db of ther-
mal noise to the electrical noise level.

Film noise will ordinarily be well
above phototube and thermal noise.
Noise due to the granular structure of
the photographic image may be 45 db
to 55 db below the signal level. For pho-
totube output levels at the magnitude
specified in the preceding paragraph,
the shot-noise level is likely to be 10 db
to 20 db below the film-noise level,
depending upon the film-noise level and
the average luminance upon the photo-
tube with film in the reproducer. A
phototube output of 300 mv d-c, though
not always attained even in 35mm pro-
jectors, is entirely feasible. A level of
nearly 450 mv was measured on the
equipment described above when operat-
ing with a gas-amplification factor of
2.3 and an equivalent slit height of
0.432 mils. The phototube should have
as high an effective physical load resist-
ance as is consistent with distortion
requirements, since signal level and shot
noise increase more rapidly as a function
of the load resistance than does thermal
noise.

Conclusion

It has been shown that the slit height
giving maximum signal-to-electrical noise
ratio in a photographic sound reproducer
may be readily calculated. The neces-
sary data are the desired overall fre-
quency-response characteristic, the pho-
totube gas-amplification factor, and the
d-c voltage drop across the phototube
effective load resistor at the illuminance
level for which the noise is to be mini-
mized. The optimum slit height so
found is undesirably large. Phototube
and amplifier noise levels become rel-
atively unimportant, thus permitting
wider choice of slit height, if the photo-
tube d-c output level, assuming a gas-
amplification factor of 6, is 300 mv or
over, without film in the machine. An
output level of this magnitude is readily
attainable.

References

1. G. Logan, "Optimum response scanning
slit-image," Electronics, 75: 140-143,
June 1942.

2. J. G. Frommer, "The optimum width
of illumination of the sound track in
sound reproducing optics," Jour. SMPE,
49: 361-369, Oct. 1947.

3. Motion Picture Research Council, Inc.,
Technical Bulletin, "Standard Electrical
Characteristics for Theater Sound Sys-
tems," p. 7, Apr. 20, 1948.

4. "Tentative Recommendations for 16mm
Review Rooms and Reproducing Equip-
ment," Jour. SMPTE, 56: 116-123,
Jan. 1951.

5. J. B. Johnson and F. B. Llewellyn,
"Limits to amplification," Bell Sys.
Tech. J., 14: 85-97, Jan. 1935.

6. G. L. Pearson, "Fluctuation noise in
vacuum tubes," Bell Sys. Tech. J., 13:
634-654, Oct. 1934.

7. N. R. Stryker, "Scanning losses in re-
production," Jour. SMPE, 15: 610,
Nov. 1930.

8. W. A. Harris, "Fluctuations in space-
charge-limited currents at moderately
high frequencies, Part V. Fluctuations
in vacuum tube amplifiers and input
systems," RCA Rev., 5: 505-525, Apr.
1941.

Discussion

Maxwell A. Kerr (Navy Department,
Bureau of Ships): What type of first tube
was in your amplifier?

Mr. Horak: I had direct coupling be-
tween the phototube and my first amplifier
tube and the first amplifier stage was a
12J5 cathode follower to lower the im-
pedance feeding the long cable to the main
amplifier.

Mr. Kerr: The reason I ask that is that
these conclusions are based on what seems
to be a cesium-type phototube. For in-
stance, there are no measurements on the
lead sulfide type, are there?

Mr. Horak: I have no measurements on
lead sulfide tubes at all.

Mr. Kerr: I see. I just wondered if
that wouldn't change the ratios on that
curve.

Mr. Horak: If the same Standard Elec-
trical Characteristic is maintained, and
if the lead sulfide tube actually has a white

386

November 1952 Journal of the SMPTE Vol. 59

noise spectrum, and the noise varies with
the light level in the same manner as shot
noise, the curves would be correct. If the
noise characteristics are known, the same
method of computation can be applied
to any type photocell. The character of
the noise introduced by the lead sulfide
tube may be different from that of shot
noise and perhaps the absolute noise level
would be greater.

Mr. Ken: Except that our experience
has been that the signal-to-noise ratio was
much higher on the lead sulfide tube.*

Mr. Horak: I'm not too familiar with
lead sulfide tubes, but I believe the noise
level is perhaps a little higher and the
signal level is much higher.

Mr. Ken: That's right.

George Lewin (Signal Corps Photographic
Center): Are the optimum values you
have arrived at by this investigation
radically different from practice in com-
mercial projectors?

* Lowell O. Orr and Philip M. Cowett,
"Desirable characteristics of 16mm enter-
tainment film for Naval use," Jour.
SMPTE, 58: 245-258, Mar. 1952. See
especially p. 249, Use of Sulfide Photo-
resistive Cell.

Mr. Horak: We measured one Eastman
Model 25 Projector and it has a slit height
of approximately 0.5 mil, which corre-
sponds to an h/\c of about 0.55. This
measurement was made without checking
the focus and azimuth adjustments.

As I pointed out, the film noise is the
dominant factor. If you have sufficient
illumination on the phototube, it doesn't
really matter, within wide limits, what slit
height you have. The determining factors
are how much do you want to equalize
and how critical do you want your adjust-
ments to be.

Anon: Can you manufacture projectors
with these optimum slit heights?

Mr. Horak: These slit heights are within
practical manufacturing ranges. The
16mm projectors need to have equivalent
slit heights of between 0.64 and 0.73 mil.

The 35mm projectors have, I believe,
a slit height of about 1.2 mils. The h/\c
of 0.71 would be equivalent to 1.64 mils —
that's the optimum for phototube noise —
that would be 1.64 mils for the 35mm re-
producers, and the standard is 1.2 mils.
The standard was apparently selected on
the basis of practical equalization rather
than on the basis of minimum electrical
noise level.

Grim wood and Horak: Reproducer Slit Height

387

Dual Photomagnetic Intermediate
Studio Recording

By JOHN G. FRAYNE and JOHN P. LIVADARY

Selected production magnetic tracks are transferred to a recorder which lays
down collinear 200-mil push-pull direct-positive variable-area and magnetic
tracks. Magnetic stripe is on base of photosensitive emulsion on the opposite
edge of film from photo track. The photo track may be used for reviewing,
cutting, etc. Re-recording is done from assembled magnetic tracks. This
method combines advantages of photo track for editing and provides superior
quality of magnetic track. Certain operating economies are made possible
by this method.

-L HE USE OF magnetic recording for
original motion picture production has
made such great strides since its intro-
duction into the studios three or four
years ago that it has now become the
almost universal medium for this type
of recording. The use of magnetic re-
cording in the subsequent studio opera-
tions, such as running of dailies, cutting,
editing and re-recording, has been very
limited to date. This hesitancy on the
part of the studio has been due to many
factors, some economic in nature, some
imposed by the unavailability of the
necessary tools — such as suitable film
splicers — and some due to the inevitable
inertia in changing over from certain

Presented on October 10, 1952, at the So-
ciety's Convention at Washington, D.C.,
by John G. Frayne, Westrex Corp., 6601
Romaine St., Hollywood 38, and John P.
Livadary, Columbia Pictures Corp., 1438
Gower St., Hollywood 28, Calif.

time-honored work practices to new and
untried techniques.

Among the latter, the cutting and
editing of the opaque magnetic sound
track have been stumbling blocks to
operators long accustomed to "reading"
the visible modulations of either variable-
density or variable-area photographic
sound tracks. Attempts have been made
to ameliorate this situation by super-
imposing so-called "modulation" writing
on the magnetic coating, or, in the case
of striped film, on the clear film base
area. This writing usually represents
a trace of the sound envelope (rather
than the individual sound modulations)
because of the difficulty of making the
writing pen follow any but the lowest
of the sound-track frequencies. Conse-
quently, the output of the magnetic
sound track is usually rectified before
being fed into the pen, and with the aid
of some electric filtering a d-c deflection
may be obtained for even a high-

388

November 1952 Journal of the SMPTE Vol. 59

frequency input. This writing usually
involves a separate operation, at a
reduced speed, to obtain a legible trace.

The method described in this paper
retains all the advantages of the standard
photographic sound-track studio pro-
cedure and combines with it the im-
proved quality and ease of operation
associated with magnetic sound re-
cording. This method also achieves
from the very start the ultimate objective
of using magnetic sound track for re-
recording purposes. In this method the
original magnetic sound track is trans-
ferred by re-recording to a special film
consisting of a standard sound-recording
photographic emulsion on which is
coated a magnetic stripe, and which
will be referred to in this paper as photo-
magnetic film. The location of the
magnetic stripe is shown in Fig. 1,
which also shows a 200-mil push-pull
variable-area track. The latter is in
the standard position for a sound-track
print even though it is recorded as a
direct-positive variable-area track. The
magnetic track is in the No. 3 position
on the Proposed American Standard
PH22.86. The standard position for
the direct-positive photographic track is
obtained by reversing the film travel
in a standard Westrex RA-1231 Re-
corder. The magnetic track may be
reproduced by reversing the film travel
in a standard single-track magnetic
sound reproducer or in the normal for-
ward direction in a triple-track repro-
ducer.1

Having obtained such a film, the
photographic track may be used for
running dailies and for the regular
editing and cutting procedures. The
magnetic track may, if desired, be used
for dailies, although its primary function
is as a re-recording medium. In cutting
the sound film standard editing practices
are followed on the photographic track,
and, since the photographic and mag-
netic modulations are in exact juxta-
position across the track, a cut across
the film insures correct synchronization

Fig. 1. Photomagnetic film sample:

(A) magnetic stripe, showing bloop;

(B) photo track.

for both tracks. This method of re-
cording does not involve any drastic
change of daily habits for the film editor
occasioned by the reading of the mag-
netic sound track or in the proper inter-
pretation of derived modulation-scribed
tracks. Rather, it affords the editor the
opportunity of gaining proficiency in the
aural editing of magnetic tracks, guided
by the parallel photographic track which
is always available for reference.

With this technique, no capital invest-
ment is required to convert review rooms.

Frayne and Livadary: Photomagnetic Recording

389

Moviolas or any other screening equip-
ment to magnetic sound reproduction,
since the regular photographic sound -
reproducing equipment may be used to
reproduce either the push-pull or one-
half thereof as a standard single track.
Only the re -recording equipment re-
quired for the final transfer to the release
photographic equipment needs to be
modified to reproduce from the magnetic
track on the composite film.

Dual Recorder

The recorder chosen for this work was
the Westrex RA-1231-C Variable-Area
Recorder as modified to lay down
a 200-mil push-pull direct-positive
variable-area track as previously de-
scribed in the Journal? The optical
schematic of the direct-positive variable-
area modulator is shown in Fig. 2. It
includes a check visual monitor and an
improved photocell monitor. In the
latter the ingenious scheme is employed
of using the light transmitted through
the ribbons for actuating the photocell
monitor, the light reflected from the
ribbons being used to expose the photo-
sensitive emulsion.

The recorder was further modified
by adding a magnetic recording kit
similar to that described in the March
1950 Journal? Since the film travel
is in the reverse direction, the monitor
head has been moved as shown in Fig.
3 to a position above the recording head,
instead of to the customary position be-
low and to the right of the latter. The
location of the recording head at the
drum position makes it possible to make
the magnetic and photographic lines of
translation exactly collinear. In fact,
the location of the recording head at
any other position in the recording
machine would defeat the purpose of
this dual-recording technique. One
of the problems encountered in this
recorder was the tendency to partial
magnetization of the recording head by
the stray field from the light-valve per-
manent magnet. This was somewhat

alleviated by placing a sheet of mu-
metal between the modulator and film
compartments of the recorder. Under
this recording condition, an overall
signal-to-noise ratio of about 55 db is
readily obtained on the magnetic track.
Since this is considered satisfactory in
view of the ultimate transfer to a stand-
ard photographic release track, no
further isolation of the disturbing source
of magnetization seems to be imme-
diately warranted.

Film

The film used to date in this process
is the Eastman Fine Grain Sound
Recording Safety Film, Type 5372
(35 mm), variable-area type film with
the magnetic stripe added to the base
side of the photosensitive film. The
pioneering work in the coating of this
raw stock was carried out by Reeves
Soundcraft Corp., and in spite of the
rather hazardous process of working
with a light-sensitive film the production
of the early batches of the dual-purpose
film has been singularly free of serious
defects. Further experience should tend
to make this operation a purely routine
affair. The processing of the film is
handled in the film laboratory without
any precautions other than those dictated
by normal operating practice for the
proper development of variable-area
tracks. No damage to the magnetic
stripe by the photographic developing
process has been observed.

The Record-Reproduce
Transmission System

The transmission system of the photo-
graphic-magnetic transfer channel in
use at Columbia Pictures Corp. is shown
in block-schematic form in Fig. 4. The
original magnetic recording is re-
produced by a modified RA-1251 Re-
recorder, the signal being fed to a
dividing network through a level-control
attenuator and line amplifier. The
dividing network provides two input
signals, one of which is recorded by

390

November 1952 Journal of the SMPTE Vol. 59

LAMP

45° MIRROR. NOT SHOWN

CYLINDRICAL / X.

OBJECTIVE f \

Irt [ RECORDING \
Wh DRUM

V '

Fig. 2. Variable-area modulator optical schematic.

Fig. 3. Dual photomagnetic recorder.
Frayne and Livadary: Photomagnetic Recording

391

PHOTOGRAPHIC CHANNEL

RECORDING
AMPLIFIER

BIAS
OSCILLATOR

MAGNETIC CHANNEL
Fig. 4. Block schematic of dual recording channel.

the photographic channel, the second
being recorded by the magnetic channel.
The photographic channel consists of a
film loss equalizer, limiting and peak-
chopping amplifier, low-pass filter, light-
valve attenuator and noise-reduction
amplifier. This photographic channel
supplies the signal for the photographic
modulator of the RA-1231-G Recorder.
The magnetic channel consists of an
attenuator, line amplifier, low-pass filter,
recording amplifier which also provides
equalization, and a bias oscillator and
filter. The magnetic channel supplies
the signal for the magnetic recording
head in the RA-1231-C Recorder.

The PEG mesh of the RA-1231-G Re-
corder is connected to an external
amplifier which in turn feeds the monitor
amplifier and speaker for monitoring
the photographic channel. The mag-
netic monitor head in the RA-1231-C
Recorder is connected to an external
magnetic-reproducer amplifier which
feeds the monitor amplifier and speaker

so that the magnetic channel may be
monitored. Suitable switching is pro-
vided so that the operator may select
the channel to be monitored.

Recording Frequency Characteristic

Photographic Channel. The film loss
equalizer plus the normal light-valve
resonance rise is used to correct the
frequency characteristic of the photo-
graphic channel. The film loss equalizer
is so adjusted that when a constant level
signal is recorded photographically, the
resultant film will reproduce "flat" when
referenced to the Research Council
standard frequency film ASFA-2 5-
521 -A. The frequency response of the
photographic channel from the input
to the light-valve transformer is shown
in Fig. 5. The film recording channel
is so adjusted that the peak chopping
point of the limiter occurs 1 db below
the light-valve clash point. The limiter
amplifier has a 20:1 ratio, the start of
limiting being 2 db below the peak

392

November 1952 Journal of the SMPTE Vol. 59

+ 15
+ 10
+ 5
0
-5

-10

RECORDING FREQUENCY CHARACTERISTIC
PHOTOGRAPHIC CHANNEL

,**

*—

00 1000 K>00<

FREQUENCY IN CYCLES PER SECOND
Fig. 5. Photo channel frequency characteristic.

+20

+15

0+10-

+•5

CALIBRATING FREQUENCY FILM

A -CONSTANT VELOCITY 6DB/ OCTAVE

B- CONSTANT CURRENT INPUT

C - HALF LOSS CURVE

D- DESIRED EQUALIZATION

10+

1000
FREQUENCY IN CYCLES PER SECOND

Fig. 6. Magnetic calibrating frequency film.

10000

+15
g+IO
Z+5

2 -5
-10

RECORDING FREQUENCY CHARACTERISTIC
MAGNETIC CHANNEL s

•••

— ,

—

— '

•

.-^•-^

00 1000 IOOOC

FREQUENCY IN CYCLES PER SECOND
Fig. 7. Magnetic-channel frequency characteristic.

Frayne and Livadary: Photomagnetic Recording

393

chopping point. During the transfer
operation, signal level is so adjusted that
peak signals are compressed approxi-
mately 4 db. Operating under the
above conditions the distortion of the
photographic track at a level just below
the peak chopping point is 1.8% at
400 cycle/sec, and the signal-to-noise
ratio is approximately 50 db.

Magnetic Channel. The magnetic re-
cording channel is provided with low-
and high-frequency pre-equalization in
order to improve the signal-to-noise
ratio of the magnetic track. The low
frequency pre-equalization amounts to
5 db at 50 cycle/sec, this amount of
equalization being based on the energy
distribution of speech and music so that
the magnetic film will not be overloaded
at low frequencies.

The high frequency pre-equalization
is adjusted to compensate for half of
the overall film recording and repro-
ducing losses. In order to determine the
shape and amount of this equalization,
a frequency film was recorded at normal
bias current while maintaining constant
audio current through the recording
head. This frequency film was then
reproduced over the same magnetic
head by means of a flat amplifier using
a high-impedance grid input, voltage
amplifier and cathode follower output
stage. The frequency film has a charac-
teristic similar to that shown in Fig. 6.
On this characteristic curve a constant
velocity (6 db per octave) line A-B was
drawn. It was then assumed that the
deviation of the measured response from
the constant velocity line was a measure
of the recording and reproducing losses,
such as slit reproducing losses, de-
magnetization, etc. The losses meas-
ured by this method were then divided
in half and pre-equalization was intro-
duced into the recording characteristic
to compensate for one-half of the
measured loss. In practice this equali-
zation amounts to approximately 10
db at 8000 cycle/sec. After the high-
and low-frequency pre-equalization

characteristic had been determined by
the above method, a standard three-
track frequency film was recorded. This
standard film was used to adjust all re-
producer equalization to a common
standard. The recorder equalization
was then adjusted so that a magnetic
film recorded on the photographic-
magnetic recorder would reproduce
"flat" on any of the calibrated re-
producers. The frequency response of
the magnetic recording channel from
the input to the output of the recording
amplifier is shown in Fig. 7.

The gain of the magnetic channel is
so adjusted that the 1% distortion point
at 400 cycle/sec of the magnetic film
occurs for the same input signal which
causes peak chopping in the photo-
graphic channel. Under these condi-
tions, the signal-to-noise ratio of the
magnetic track is approximately 55 db.
This relatively low value of signal-to-
noise ratio is due to the magnetic flux
introduced into the recording head by
the leakage flux of the permanent magnet
of the light valve.

Studio Routines

This method was first introduced at
Columbia Pictures on May 19, 1952.
In order to study its effect upon normal
editorial procedures, it was introduced
without any forewarning to the editorial
department. The only information
transmitted to the film editor was to
the effect that he should ignore the
magnetic sound track and edit the
photographic track in the usual manner.
When he finished editing the first
picture, the film editor commented that
he objected slightly to reducing the
transparent area adjacent to the normal
photographic sound track by the applica-
tion of the magnetic stripe. This re-
duced his field of vision while running
the sound and action film superimposed
and made it difficult for him to follow
some of the action on the fringe of the
picture frame.

394

November 1952 Journal of the SMPTE Vol. 59

During re-recording it was found that
the quality of the magnetic stripe was a
faithful copy of the original magnetic
recording. Apparently the processing
of the photographic sound track had
resulted in no ill effects on the magnetic
track, which confirmed pre-production
tests during which the characteristics
of the magnetic sound track were
checked before and after film processing.

Normal overlap film splices were
used in splicing this film. In running
the magnetic sound track some of these
splices proved to be silent and some
noisy. It was found that magnetized
shears and cutting blades of the regular
film splicers were mostly responsible for
this effect. It was also observed that
certain splices had a microphonic effect
upon the magnetic head due to the im-
pact of the lower edge of the film splice
upon the magnetic head.

This last observation revealed that
film splices were silent when made in
one particular direction, which luckily
happened to be the normal way of mak-
ing splices on photographic film.

The splice noise was eliminated by
punching a diamond-shape hole (see
Fig. 1) over the magnetic splice, as is
done on photographic negatives. An-
other method was to notch the film at
each splice and momentarily short-
circuit the recording system by a micro-
switch operated from these notches.
Still another solution involved the
momentary lifting of the splice from the
magnetic head by the application of a
triangular piece of adhesive paper on
the splice.

Some of the first samples of this
photographic film exhibited severe edge-
wave and spoking of the film roll. These
defects have long been present to a
minor degree in standard motion picture
film but were apparently exaggerated
in adding the magnetic stripe to the
base of the sensitized film. They have
been largely removed through the co-
operation of the manufacturer of the
striping process. Another difficulty,

pressure densitization of the photo-
graphic emulsion, due to too tight
winding of the film rolls after adding the
stripe, was also present in some of the
early samples. This defect, too, has
since been eliminated by more careful
attention to proper rewinding of the
coated film.

The location of the balance stripe
was also given some thought. Some
film was manufactured with the balance
stripe along the outer edge of the
sprocket holes on the side of the photo-
graphic sound track. Other film was
manufactured with the balance stripe
located along the inner edge of the
photographic sound track. Both posi-
tions were tried since at the beginning
it was not1 quite clear whether the
manufacturer's edge numbers on this
film would be of any importance in film
editing, and provision was therefore
made to leave the edge numbers visible.
Later, however, it was decided that
these numbers had no particular sig-
nificance and the balance stripe was
moved to the outer edge of the film.

In projecting the photographic track
on normal projection equipment, it
was found that the thickness of the
magnetic stripe caused a slightly out-of-
focus condition which resulted in a loss
of 1 db at 7,000 cycles. This was more
evident when the balance stripe was
placed adjacent to the photographic
sound track because the magnetic stripe
and the balance stripe were both riding
the scanning drum, which caused the
photographic film to be out of focus by
the thickness of the magnetic emulsion.
However, the later removal of the
balance stripe to the outer edge of the
film placed the photographic track in a
more favorable position and practically
eliminated this out-of-focus condition.

Benefits of the Method

The benefits derived by this method
so far are as follows :

1 . It eliminates the need for introduc-

Frayne and Livadary: Photomagnetic Recording

395

ing magnetic equipment in the pro-
jection rooms.

2. It introduces 1 00% magnetic opera-
tion without causing any disturbance in
the editorial department.

3. It eliminates photographic re-
recording masters and substitutes a
magnetic sound track for re-recording
purposes.

Economic Considerations

Experience with this recording method
at Columbia Pictures has shown that
there is a definite reduction in cost as
compared to the normal negative-posi-
tive photographic recording method as
practiced at the studio. However, due
to the downward trend in costs of mag-
netic striped film and also due to such
alternate methods as the use of 17^mm
instead of 35mm and the substitution of
a lower-cost fine-grain positive for the
premium 5372 emulsion, it is difficult to
set down in figures what the ultimate
savings might be in the method of re-
cording described in this paper. A con-
siderable saving results from the elimi-
nation of master photographic re-
recording tracks which amounts to an
average figure of $500 per picture at
Columbia.

It is too early yet to thoroughly
evaluate completely the full effect and
future potentialities of this particular
method. This method was originally
developed as an interim measure de-
signed to promote the gradual education
of the film editors at Columbia Pictures
in the handling of magnetic films prior
to the introduction of 100% magnetic-
recording methods. It is quite possible,
however, that because of the advantages
shown above this method may eventually
develop into a strong competitor to the
all-magnetic recording method which is
the ultimate objective of the motion
picture industry.

The authors wish to acknowledge the
invaluable aid of Lloyd Russell of

Columbia Pictures in getting this re-
cording system into practical use in the
studio. They also wish to thank Reeves
Soundcraft Corp. for their cooperation
in making this film available and in
endeavoring to meet the particular
studio requirements for the successful
operation of this photo-magnetic film
method.

References

1. C. C. Davis, J. G. Frayne and E. W.
Templin, "Multichannel magnetic film
recording and reproducing unit," Jour.
SMPTE, 58: 105-118, Feb. 1952.

2. L. I. Carey and Frank Moran, "Push-
pull direct-positive recording," Jour.
SMPTE, 58: 67-70, Jan. 1952.

3. G. R. Crane, J. G. Frayne and E. W.
Templin, "Supplementary magnetic
facilities for photographic sound sys-
tems," Jour. SMPTE, 54: 315-327,
Mar. 1950.

4. Eastman Kodak Company, Common
Cause of Damage to 35mm Release Prints,
1952.

Discussion

J. E. Aiken (Naval Photographic Center):
Many studios prefer the use of variable-
density sound tracks. I would like to ask
Dr. Frayne if there is any reason why
this method may not be used with variable-
density sound tracks. While I have the
floor, I would like to ask a second question.
What precautions should be taken in the
film laboratory in processing and are any
changes in techniques and equipment
required in the film processing laboratory?

Dr. Frayne: There's no reason what-
ever why you could not use variable-
density instead of variable-area, provided
that you have a variable-density direct-
positive. There was a paper published
in the Journal about a month ago by O. L.
Dupy, which I had the privilege of pre-
senting for him at the Chicago Convention,
in which is outlined a direct-positive
variable-density system which is currently
being used on an experimental basis at
M-G-M. If that or some similar method
works out, there is no reason why it cannot
be used. The problems are the same for
either method as far as equipment is

396

November 1952 Journal of the SMPTE Vol. 59

concerned. With regard to the second
problem, all I know about the laboratory
problem is that I have been assured by
Mr. Livadary and the laboratory people
at Columbia that no extra precautions
have to be taken in handling this film in
the laboratory. Does that answer your
question?

Mr. Aiken: Thank you.

George Lewin (Signal Corps Photographic
Center): Is this type of magnetic film
fully as good as a regular full-width
magnetic film in sound quality?

Dr. Frayne? I have been assured that

the striped film now in production is of
comparable quality. At first, I believe,
there were some difficulties. I think that
somebody in the audience from one of the
film-coating companies could answer that
question better than I can.

Edward Schmidt (Reeves Soundcraft
Corp.): John, you're quite right. The
early films did have problems. But I
feel that the present product that we
manufacture is equivalent to the current
full- width 35mm magnetic film, without
any question.

Dr. Frayne: Thank you.

Frayne and Livadary: Photomagnetic Recording

397

Television Facilities of the
Canadian Broadcasting Corporation

By J. E. HAYES

This paper describes the television stations which the Canadian Broadcasting
Corporation has built in Montreal and Toronto for the inauguration of tele-
vision broadcasting in Canada. In planning these stations certain special
requirements had to be met such as the necessity for programming in two
languages in Montreal and the need for producing a relatively large per-
centage of locally originated shows in both cities.

AT MIGHT BE SAID that the first official
step in the development of a Canadian
television service was taken in January
1950 when the Governor-in-Council
approved a loan of $4,500,000 to the
Canadian Broadcasting Corp. for the
purpose of establishing television stations
in Montreal and Toronto. Actually, of
course, much work had preceded this
action. We had kept in close contact
with progress in England, France and
the United States, and had prepared for
our management detailed reports cover-
ing technical, program and financial
aspects of television. The Board of
Governors of the CBC was in a position
therefore to make recommendations
to the Canadian Government with a full
knowledge of the existing television
situation in other countries and the
probable effect of its impact on Canada.
Detailed engineering work was started

Presented on October 6, 1952, at the
Society's Convention at Washington, D.C.,
by J. E. Hayes, Canadian Broadcasting
Corp., P.O. Box 6000, Montreal, Canada.

immediately and a position of Coordi-
nator of Television established to ensure
coordination of the planning of the
program, engineering, policy and finan-
cial aspects of the project. The duties of
this post were undertaken by J. A.
Ouimet who was, at that time, Chief
Engineer. Appointments were made of
the key personnel for both the Montreal
and the Toronto stations in order to
permit the organization of the operating
staff during the period of construction.
A senior position, reporting directly to
Management, of Director of Television,
was established for each location and,
under him, positions of equal responsi-
bility, Technical Director and Program
Director. These men, with their re-
spective assistants, formed the nucleus
of the operating group for each station
and under the general guidance of the
Coordinator were given the responsi-
bility of developing program plans,
determining staff requirements and set-
ting up training and hiring schedules
timed to fit with expected completion
dates for the stations.

398

November 1952 Journal of the SMPTE Vol. 59

Throughout all this preliminary work,
special emphasis was placed on complete
cooperation between program and engi-
neering since it is our conviction that
only through such cooperation is it
possible to achieve the best results. This
teamwork is quite necessary even during
the design of the stations since the
design engineers must be kept informed
regarding program plans in order to be
in a position to provide the most suitable
equipment. On the other hand pro-
gram plans must be developed with a
consciousness of the cost of technical
facilities which may be required by the
programs envisaged.

The two stations which are now in
operation in Montreal and Toronto are
the result of this type of cooperative
effort and we believe the result will
justify the amount of planning and
thought that has gone into their develop-
ment. Actually, we had hoped to be in
operation several months earlier, but
shortages of steel for towers, delayed
deliveries of electronic components and
other incidents of a completely non-
technical nature have hindered our
progress.

Technical Facilities: The faci'ities sup-
plied in the two stations are, in general,
the same, although there are certain
minor differences which were brought
about by local conditions. Basically,
each station consists of two studios,
film recording and reproducing facilities,
a mobile unit, a 5-kw picture transmitter,
and a 3-kw sound transmitter. In
Toronto this equipment and office space
for technical and production personnel
are housed in a five-story building located
in the center of the city. The antenna,
a 6-bay turnstile, is mounted at the top
of a 500-ft self-supporting tower which
is adjacent to the main building. The
transmitter operates on channel 9
(186 to 192 me) with an effective radiated
power of 26 kw.

In Montreal, the transmitter and
studios are separated. The television

studios are located in a new five-story
annex to the Radio-Canada Building, a
twelve-story structure which houses our
engineering offices and all our sound
studios and operations personnel for
the Montreal area. The transmitter and
antenna are located on top of Mount
Royal, which is situated in the center
of the city. The tower height of 283
ft (a limit imposed by aviation restric-
tions) plus the height of the mountain
results in an overall antenna height of
about 936 ft above average terrain.
The transmitter operates on channel 2
(54 to 60 me) and with a 3-bay turnstile
antenna provides an effective radiated
power of 1 6 kw for the picture carrier.

Because of the delay in obtaining the
towers, it was found necessary to erect
70-ft temporary masts on top of the trans-
mitter buildings in both cities. Single-
bay antennas were erected at the top of
these temporary masts in order to permit
operation of the stations prior to com-
pletion of the main towers.

This rather brief description gives a
fairly general picture of the two tele-
vision installations. A more detailed
description of the Montreal station will
serve to show the extent of the facilities
being provided.

The five-story studio building is
67 X 90 X 46 ft high. It has a cube
of 455,000 cu ft, and is of fireproof
construction. This building houses two
production studios, a film recording and
reproducing room, and control rooms,
but does not include office space for
the technical and production staff of
the station.

In the basement there are scenery
shops, with woodworking and painting
sections, storage space, a room for re-
frigeration equipment, and dressing
rooms. The scenery shops are equipped
with power tools, hand tools, and paint-
ing facilities necessary for the production
of scenery. Paint-spray equipment, a
heavy-duty sewing machine, and other
necessary tools, are supplied for the
production of flats and backdrops.

J. £. Hayes: CBC Television Facilities

399

Fig. 1. Control room for the small studio. At the left of the picture is the audio
console, then the positions for the program producer and his assistant followed by the
technical producer and camera control operator.

Fig. 2. Control room for the large studio. The audio control position is at the left
of the picture; the producer and his assistant work at the central desk. Camera
control operators are seated at a lower level. The technical producer operates the
camera switching console at the right.

400

November 1952 Journal of the SMPTE Vol. 59

The first floor is occupied by the large
studio. The second floor has the control
room, observation room, announce
booth, and the upper part of the main
studio. The third floor has the smaller
studio, a storage room for props, a
clients' room, an announce booth, and
control room. The fourth floor is
occupied by the upper part of the small
studio, master control room, the film
recording and reproducing room, a
maintenance shop, film editing room,
and additional storage space. Ventilat-
ing equipment is located on the fifth
floor, which is approximately one half
the area of the other floors.

Large Studio: The large studio is
90 X 60 X 25 ft high and occupies two
stories. It is equipped with three
cameras, one of which is mounted on a
small camera crane, and the other two
are mounted on pedestal dollies. One
large and two small microphone booms
are provided, as well as video and audio
monitors, and a complete production
intercommunication system. The
cameras and all the video equipment for
both Montreal and Toronto studios were
manufactured in England, but are
similar in general design and operate
on the same standards as equipment
available in the United States. The
lighting equipment, totalling about 70
units, includes an assortment of scoops,
6-in. and 8-in. spotlights, and a few
striplights and fluorescent units. Light-
ing control panels permit individual
switching of 80 circuits, and dimmers
allow independent adjustment of 10
different banks of circuits. Pantographs
are provided to allow adjustment in a
vertical direction of 16 of the lighting
units. The control panels and wiring
are arranged to permit expansion, since
it is expected that the lighting facilities
may eventually be approximately double
the initial installation.

Small Studio: The small studio, which
is 65 X 44 X 19 ft high, occupies part

of two stories. It is equipped with
units similar to those already described,
except that there are only two cameras,
one of which is mounted on a small
camera crane, and the other on a pedestal
dolly. The number of lighting units is
approximately one half of those in the
larger studio.

No provision has been made in either
of these studios for the accommodation
of a studio audience, since it is much
more economical to use all available
space for studio production. Audience
participation shows requiring a small
audience can, of course, be handled by
bringing a limited number of people
into the studio for that particular
program.

Control Rooms: Each studio has its
own control room arranged to overlook
as much as possible of the associated
studio. The master control room is
located on the fourth floor, and has
observation windows at one end, to
permit visitors to see the equipment
without interfering with operations.
The control rooms are shown in Figs. 1
and 2, and the master control console
in Fig. 3.

Film Recording and Reproducing Facili-
ties: The film recording and reproducing
room is located on the fourth floor
adjacent to master control. The film
reproducing equipment (Fig. 4) is of
a new design using an image orthicon
camera similar to those in the studios.
It includes two 16mm projectors and
two slide projectors, all of which can
be remotely controlled.

Film recording equipment is provided
to permit the recording of television
programs on 16mm film. This equip-
ment provides a direct-positive picture
from a negative image on the tube.
With this equipment only a single print
is available, and facilities for producing
additional prints will be added later as
the need arises.

A magnetic tape recorder is located

J. E. Hayes: CBC Television Facilities

401

Fig. 3. Master control console. This console has two monitors for incoming pro-
grams, and switching, audio and order wire panels. The console accepts audio
and video signals from the studios, film reproducing equipment, network or mobile
unit microwave. These signals may then be routed to the transmitter, film recording
equipment or network as required.

Fig. 4. Film reproducing equipment and monitor rack. This equipment combines
two 16mm projectors and two slide projectors and feeds the optical output from the
projectors into an image orthicon camera visible at the rear of the unit.

402

November 1952 Journal of the SMPTE Vol. 59

in the film recording and reproducing
room, to be used, as required, for the
recording and playback of commentaries
for newsreels. It may also be used for
recording the sound portion of film
recordings as a protection against pos-
sible loss of the optically recorded sound
track during recording or processing.

Photographic Equipment: A Houston
processor for developing 16mm film is
installed in the Toronto station to permit
processing of our film recordings, news-
reels, and other 16mm films. A second
processor will be installed in Montreal
if the load becomes sufficiently heavy
to justify the additional unit. There
is also an assortment of auxiliary photo-
graphic equipment to facilitate satis-
factory editing, titling and cleaning of
films. 16mm motion picture cameras
are available for taking newsreels,
drama fills, and other similar pictures.
Still cameras, an enlarger and develop-
ing equipment are provided for the
purpose of making slides and for various
other uses around the studios.

Mobile Unit: A mobile unit equipped
with three camera chains, a microwave
relay transmitter, and all necessary
auxiliary equipment is used for televising
sports, special events and other subjects
outside the studios.

Normally, the microwave transmitter
for the mobile unit relays the signal back
to a receiving point on top of the Radio-
Canada Building, but in the event that
a line-of-sight path does not exist be-
tween the remote location and this
receiving point, a second receiving point
is available on the transmitting tower.

Transmitter Building: The Montreal
transmitter building (Fig. 5) is located
on the top of Mount Royal on a site
which has been leased to us by the City.
The building is large enough to house
two 5-kw transmitters with the asso-
ciated 3-kw sound transmitters and in
addition, the two 3-kw frequency modu-

lated VHF transmitters which are at
present operating from the Keefer
Building in Montreal. Some extra
space has been set aside to permit future
power increases of the television trans-
mitters.

The antenna tower is located adjacent
to the transmitter building. At a
height of 120 ft above the base there is
a platform to support the microwave
receiving equipment to be used, when
required, with the mobile unit. Above
this is a straight section of tower de-
signed to take a 6-bay "super-gain" type
antenna to be used in conjunction with a
future second television transmitter on
channel 6. Then follow two "pylon"
type antennas for the two frequency-
modulated transmitters and finally, at
the top, the 3-bay turnstile antenna for
the present television transmitter.

Television Network: The CBC has
entered into a contract with the Bell
Telephone Company of Canada for a
television network connecting Toronto
and Montreal via Ottawa and, as well,
for a link with the United States tele-
vision networks via Buffalo, N.Y. A
chain of microwave relay stations is
under construction along the 374-mile
route and, although it is not expected
that the complete network will be ready
for use before May 1953, the section
between Buffalo and Toronto is now in
operation. It appears probable that
this network could be extended eastward
as far as Quebec City and westward as
for as Windsor, Ontario, before very
long, but a coast-to-coast network across
Canada seems to be in the somewhat
more distant future. Plans are now
underway for the construction of tele-
vision stations in Vancouver, Winnipeg,
Ottawa and Halifax. The Ottawa
station will normally be fed via the
network from the Montreal and Toronto
production centers, but will have facili-
ties for originating programs of special
interest from the Capital City. The
stations in Vancouver, Winnipeg and

J. E. Hayes: CBC Television Facilities

403

Fig. 5. Transmitter building and antenna structure. The transmitter is located
on top of Mount Royal. The turnstile antenna at the top is for the present television
transmitter on channel 2. The tubular section consists of two pylon antennas for
frequency modulation transmitters. The illustration also shows an antenna for a
future transmitter on channel 6. The balcony will support a microwave receiving
antenna for use in conjunction with the mobile unit at times when the latter is not
within line-of-sight of the studio building.

Halifax will depend on kinescope re-
cordings of Montreal and Toronto pro-
ductions for most of their schedule, but
they will have sufficient facilities for a
limited amount of local production.

Program Plans: The recent report of
the Royal Commission on National De-
velopment in the Arts, Letters and
Sciences, more popularly known as the
Massey Report, made certain recom-
mendations with regard to the objec-
tives which should determine the choice

of material for Canadian radio and tele-
vision programs. Guided by these
recommendations, the CBC intends to
make full use of this new and tre-
mendously effective means of expression
in the development of Canadian talent
and ideas. We believe that it should
be used not only as a means of enter-
tainment, but also as a medium for the
awakening of a greater appreciation and
a better understanding of the more
important fields of human endeavour.
The incorporation of this ideal into

404

November 1952 Journal of the SMPTE Vol. 59

a balanced and diversified program
schedule requires that the CBC should
keep control over the type and quality
of all programs it carries. Conse-
quently, commercially sponsored pro-
grams will be accepted only when the
CBC considers them to be of sufficiently
high quality and of suitable content.

Programs are being produced in two
languages — English in Toronto and
French and some English in Montreal.
In addition, the film-recording equip-
ment permits an exchange of pro-
grams between the two cities prior
to the completion of the microwave
network. Experience in sound broad-
casting has proven that a bilingual
program service is not entirely satis-
factory to the majority of listeners, and
it is expected that before long a second
transmitter will be installed in Montreal
to permit independent programs for
the French and English viewers. The
completion of the network between
Toronto and Montreal will make the
addition of the second transmitter a
logical step. This will not be too
difficult to do from a technical stand-
point since the layout of the existing
equipment has been made in such a
manner that the second transmitter
with its associated facilities may be
added and integrated with the existing
equipment.

The two stations began a limited
television service during August and
the official inauguration of the service
took place early in September. The
initial program schedule is being limited

to approximately three hours in the
evening with the expectation that the
number of hours will be increased
gradually as the service develops.

Discussion

Louie L. Lewis (WOI-TV, Ames, Iowa):
Are you going to distribute your programs
by relay only, or are you going to dis-
tribute them by kinescope also?

Mr. Hayes: We will have to use kine-
scope recordings to feed Winnipeg, Van-
couver and the Maritimes Station. We
foresee the microwave network extending
east of Montreal to Quebec City and west
of Toronto as far as Windsor, but it may
not be economical to extend it farther.
At present we are exchanging programs
between Montreal and Toronto because
the network is not yet operating between
these cities.

Mr. Lewis: Are you going to make
positives and negatives then, and make
copies?

Mr. Hayes: We expect to do so as soon
as additional stations are in operation.
For the moment we are not making any
prints but are sending the one and only
copy from one station to the other.

Barton Kreuzer (RCA, Camden, N.J.):
How many stations of the Canadian
Broadcasting Corporation are operating
now, TV stations?

Mr. Hayes: Two. Just the one in
Montreal and the one in Toronto, and we
have four more under construction.

Mr. Kreuzer: Where are those four?

Mr. Hayes: Winnipeg, Vancouver,
Ottawa and one in the Maritimes. Actu-
ally the physical construction hasn't
started, but we are locating sites and
carrying out the engineering on these
stations.

J. E. Hayes: CBC Television Facilities

405

Use of Ansco Color Film
in Commercial Production

By REID H. RAY

The selection of a 35mm color film for the documentary or commercial motion
picture producer is a problem of choosing an economical and, from a proc-
essing standpoint, a practical type of color film. Both color and black-and-
white (35mm and/or 16mm) are sometimes required and a color film which
adequately fills such requirements is described here.

'OCUMENTARY and commercial mo-
tion picture producers frequently must
supply to their sponsors 35mm and
16mm color prints, and for television
either 35mm or 16mm black-and-white
prints. A color film which might be
used for multiple purposes would be an
economical as well as a practical
medium. Production time would be
saved, as one crew, with a single camera
setup, could produce a master 35mm
color negative.

An acceptable 35mm negative-posi-
tive type of color film, which meets the
requirements of such multiple duty, has
been in use at our studio since April
1951. From the one original color
negative, four types of release prints
have been made (Fig. 1 ) :

1. 35mm color prints,

2. 16mm color prints,

3. 35rnm black-and-white prints, and

4. 16mm black-and-white prints.

Presented on October 18, 1951, at the
Society's Convention at Hollywood, Calif.,
by Reid H. Ray, Reid H. Ray Film
Industries, Inc., 2269 Ford Parkway,
St. Paul 1, Minn.

The material used is "Ansco 35mm
Color Camera Film, Type 843, Daylight
Balance." This film supersedes Ansco
Type 735, a reversible color material
which was discussed by the author in a
previous paper published in the Journal.^
The characteristics of this color negative
have been described in the Journal.2
This paper will describe the use of this
color film in the commercial field. (A
demonstration reel was shown at the
conclusion of the paper.)

The speed of Type 843 Ansco Color
Negative is rated at ASA 10 and an
ultraviolet 16 filter is recommended for
both interior and exterior photography.
Arc illumination is used for interiors
with Y-l correction filters on high-
intensity arcs. Both incident and re-
flected light readings are taken in various
locations on the set to check evenness of
illumination. To achieve a warmer
tone in a background, 5-kw or 2-kw
solar spots may be added to supplement
the key- and backlighting from arcs.

For exterior photography with this
type of color film, as in all color work,
bright, clear sunlight is a prime requisite,
and generally the rule of "the sun

406

November 1952 Journal of the SMPTE Vol. 59

ORIGINAL

HsSMMANSCO H|
E 843 COLOR 3
P NEGATIVE ^

CONTACT CONTACT CONTACT
PRINTING PRINTING PRINTING

H 35MM B&W
J MASTER
C POSITIVE

35MMANSCO H
848 COLOR J

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-^OPTI
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DUPE 1
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I6HMKOOA-M g AN;

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RELEASE PRINTS

Fig. 1. Methods of release printing from Ansco 843 Color Negative.

behind the camera" holds. However,
very pleasing and excellent results have
been achieved with sidelighting. Close-
ups of characters completely back-
lighted by the sun, and frontlighted
by booster lights or aluminum-foil re-
flectors show good latitude in the flesh
tones.

Makeup used for interior photography
for men is Max Factor No. 27 Pancake
sparingly applied. For women, ordi-
nary street makeup is recommended.

The exposed negative material which
our studio produces is sent to the Houston
Color Film Laboratories for developing
and printing. A brief summary of these
processes are3:

Reid H. Ray: Color in Production

407

Fig. 2. Houston-Fearless Scene Tester — used for making scene test
strips for color prints.

The negative material is developed
in a color developer containing a non-
toxic color developing agent called S-5.
The negative is developed approxi-
mately 10 min, based on a gamma of
0.85 for the cyan layer of the monopack
film. The film is then short-stopped,
hardened, washed, bleached, washed,
hypoed, washed and dried.

A scene test for prints from Ansco
843 Negative is similar to a cinex, the
main difference being that each frame
on the strip is made from a different
filter balance, but each frame receives
the same printing light intensity. This
necessitates three tests being made on
each scene, generally three printer
points apart, in order to give a density

range. The scene tests are developed
in a positive developer similar to the
negative developer, except that it does
not have an accelerator in the solution.

The negative is timed from the scene
tests. Separate filters are made up for
scene-to-scene color correction and a
modified Bell & Howell printer with an
automatic filter changer handles the
filter combinations (Fig. 3). This filter
change is made in conjunction with the
notch used for the printer light changes.

The positive stock used is Ansco Type
848 and is developed to a gamma of
2.30 on the red record, being the cyan
layer.

The sound is printed from a black-
and-white negative track. In order to

408

November 1952 Journal of the SMPTE Vol. 59

Fig. 3. Modified Bell & Howell Model D Printer with filter bins. A: feeding

bin; B: receiving bin. Filter passes from feeding bin to position in

front of light, to receiving bin.

obtain normal transmission through the
optical system, since the positive stock
is a monopack film, it is necessary to
redevelop the track area with an applica-
tion of a viscous solution containing a
high-energy developer. With the track
area so treated there is no difference in
sound level between this type of color
print and a normal black-and-white
print.

When 16mm color prints are required
they are made from a 35mm "soft"
color print by optical reduction to a
16mm color duplicating stock. The
sound is optically reduced from a 35mm
re-recorded direct positive track.

A satisfactory 35mm black-and-white
negative can be produced by using the
original color negative to print a fine-
grain master print on Eastman 5365
stock and by developing this to a gamma
of 1.2. From this, a duplicate negative
is made on Eastman 5203 or similar
duplicating negative material. This du-
plicate negative is developed to a gamma
of 0.66.

The commercial producer works with-

out benefit of large budgets and he
must turn out color motion pictures
under conditions not always conducive
to extensive production conveniences.
The producer who wishes to operate with
a minimum crew and regular black-and-
white camera equipment, may use a
multipurpose color film described in
this paper to good advantage.

(The demonstration reel consisted of:
first, a 35mm color print, followed by
portions of the same footage in 35mm
black-and-white print from the dupe
negative.)

References

1. Reid H. Ray, "Use of 35mm Ansco
Color Film for 16mm color release
prints," Jour. SMPE, 53: 143-148,
Aug. 1949.

2. Herman H. Duerr, "The Ansco Color
Negative-Positive Process for motion
pictures," Jour. SMPTE, 58: 465-479,
June 1952.

3. Data furnished in 1951 by Robert F.
Burns, Laboratory Manager, The Hous-
ton Color Film Laboratories, Inc.,
Burbank, Calif.

Reid H. Ray: Color in Production

409

A Fast-Acting Exposure Control System for
Color Motion Picture Printing

By JOHN G. STREIFFERT

An illuminating system in a contact-printer for color motion pictures is de-
scribed. Light from a single lamp is divided into three beams which are
independently filtered, controlled in intensity, and projected onto the printer
aperture. Intensities of the red, green and blue components of the exposing
light are measured continuously and photoelectrically and compared with
reference voltages which are the analogs of the desired intensities and which
are controlled by a perforated tape according to the predetermined require-
ments of each scene to be printed. Any errors between measured intensities
and desired intensities, i.e., between photocell outputs and reference voltages,
are amplified and applied to servomotors which rotate vanes in the respective
beams until the correct intensities are established. A response time of the
order of 1/50 sec has been achieved, and the intensity of the printing light
is substantially independent of lamp current and age. A manual control
on each of the reference voltages provides for emulsion-to-emulsion variations
in print stock.

.xTLN ILLUMINATING system in a con-
tinuous contact printer used for making
motion picture color prints must fulfill
many requirements. The more difficult
requirements to attain are:

1. Sufficient illumination to expose
the color positive material at a printing
speed of at least 100 fpm.

2. Provision for control of exposure
and/or color balance to compensate
for scene-to-scene variations in negative
density and color balance and for
emulsion-to-emulsion variations of the
positive material. The change in ex.

Communication No. 1517 from Kodak
Research Laboratories, a paper presented
on October 8, 1952, at the Society's
Convention at Washington, D.C., by
John G. Streiffert, Eastman Kodak Co.,
Kodak Park Works, Rochester 4, N.Y.

posure or color balance should be made
in a sufficiently short time so as not to
be perceptible in the projected picture.
Ideally, this change should occur within
the frame line. In practice, an operat-
ing time of one frame is considered satis-
factory, provided there is no overshoot
in the system which would cause one
frame to be noticeably lighter than
adjacent frames.

In addition to these two requirements,
it is desirable that the exposure and color
balance be substantially independent of
the operating voltage and the age of the
lamp; that the power consumption of
the light source be moderate; and that
the optical, electrical and mechanical
elements of the system be simple and
reliable.

An optical and exposure control

410

November 1952 Journal of the SMPTE Vol. 59

Condenser
Lens

Rotate ble Objective Semi-
Vane Lens Mirror

Printer
Gate

Diffuser
Photocell

Chopper

Fig. 1. Schematic drawing of a projection-type optical system
with servocontrol of intensity at printer gate.

system designed to meet these require-
ments is described below.

A simple projection-type optical sys-
tem with a high-aperture condenser lens
and a high-wattage lamp is illustrated
schematically in Fig. 1 . The condenser
lens forms an image of the lamp filament
in the objective lens, and the objective
lens, in turn, forms an image of the
uniformly illuminated condenser lens
in the printer aperture. One method
of controlling the intensity of illumina-
tion at the printer aperture without
affecting uniformity is to change the
aperture of the objective lens by means
of an iris diaphragm or other mechanical
masking means, such as the rotatable
vane placed near the lens (Fig. 1).

In general, however, the intensity
will not change linearly with changes in
position of the iris or the vane, because
of the nonuniform structure of the fila-
ment image. The necessity for a cali-
brated relation between intensity and
vane position can be obviated by means
of a servosystem in which the intensity
is measured photoelectrically and ad-
justed automatically and continuously
to the correct value (Fig. 1). This is
done by comparing the voltage de-
veloped by the photocell with a reference
voltage, shown schematically as the
output of the potentiometer. Any differ-
ence between these voltages is amplified
and fed into the servomotor which rotates

the vane in a direction to reduce the
error. The reference voltage set up
by the potentiometer is thus the analog
of the desired exposure, and scene-to-
scene changes in exposure can be made
simply by readjusting this reference
voltage.

An additive system of color exposure
requires three simultaneous exposures,
red, green and blue, whose intensities
are controlled individually and pref-
erably independently. In Fig. 2 is
shown an optical system in which three
beams are derived from adjacent seg-
ments of a common condenser lens.
Mirrors reflect light from the upper
and lower segments of the condenser
lens into prisms which direct these
beams onto the printer aperture at
angles of 15° to the central beam. The
sizes of the prisms are chosen to compen-
sate for the difference in path length
between the outer and central beams;
in this way, identical objective lenses
can be used in the three beams. Red,
green and blue filters at the objective
lenses substantially restrict the exposure
of each beam to one of the three color
primaries. A beam-splitting mirror re-
flects a small fraction of the filtered light
onto an opal glass which acts as an
integrator. Beneath the opal glass are
three photocells with red, green and
blue filters over them. The output
voltages of the three photocells are

J. G. Streiffert: Control for Color Printing

411

Fil

Aperture-^

Condenser 'OOOw. Mi"w
PonTcompensating system Lomp
Prism

Photocells

Fig. 2. Schematic drawing of projection-type optical system for controlled
additive trichromatic illumination using a single lamp.

compared with three reference voltages,
which are the analogs of the desired
red, green and blue exposures. Any
difference between photocell and ref-
erence voltage is amplified by one of
three amplifiers and applied to the
appropriate servomotor to reduce that
difference to zero.

Figure 3 shows a Bell & Howell Model
D Printer which has been modified to
incorporate the optical system shown in
Fig. 2. The outer half of the sprocket
was removed to eliminate interference
of the sprocket hub with the central
light beam. The original light-control
shutter mechanism was discarded. In
its place a steel block was provided
which carries bearings for a film-driven
flange which supports the outer edge
of the film in place of the original outer
half of the sprocket.

The original cylindrical lamphouse
has been replaced with a square box
which houses the lamp and the optical
system. The cylindrical housing on
the front of this box houses one of the
servomotors. The other two motors
are on the rear side of the box. At the
extreme right is the electronic comple-
ment consisting of the power supply
below, above that the amplifier box, and
on top a tape-controlled contactor.
This contactor reads timing information

which is stored in the form of an array
of holes punched in a strip of 1 6mm film.

Figure 4 is an interior view of the
lamphouse showing the optical system.
Two of the rotatable vanes can be seen
to the left of the prisms. The third is
seen in the foreground protruding from
the hinged cover. The outer film-
supporting flange has been removed to
show the plate which holds the beam-
splitting mirror on its back side. The
photocell enclosure has also been re-
moved to show the three photocells
beneath the sprocket enclosure.

The 16mm control tape is advanced,
one frame at each scene change, by
means of a solenoid to establish a new
set of reference voltages. In the ampli-
fier circuit of Fig. 5, the tape-controlled
contactor controls a battery of fifteen
relays, five for each color, which, in
turn, control attenuators in the re-
ference voltage circuits. These at-
tenuators are calculated to provide
attenuations of 0.4, 0.8, 1.6, 3.2 and 6.4
db, which are equivalent to exposure
changes of 0.02, 0.04, 0.08, 0.16 and
0.32 log E. If several relays are ener-
gized, these attenuations add, so that
a total exposure range of 0.62 log E in
steps of 0.02 log E is provided for each
color. The three knobs shown on the
front of the amplifier box, Fig. 3, are

412

November 1952 Journal of the SMPTE Vol.59

Fig. 3. Printer with new lamphouse. Control tape reader,
servoamplifiers, and power supply are at right.

Fig. 4. Interior of lamphouse and optical system.
J. G. Streiffert: Control for Color Printing

413

PRINTED
PECS GALVO'S

Fig. 5. Schematic circuit of servoamplifiers.

manually controlled attenuators used
for setting the operating range of the
automatic system and for any compensa-
tion for emulsion-to-emulsion differences
in the print stock.

The comparison between photocell
output and reference voltage is made by
means of an electromagnetic chopper.
This chopper switches the input to a
three-stage amplifier from the photocell
output to the reference voltage 480
times per sec. Thus, any unbalance
between the photocell output voltage
and reference voltage is transformed into
a 480-cycle signal. The amplifier out-
put is synchronously rectified by a
second chopper.

The servomotors are heavy-duty
d'Arsonval galvanometer movements
originally designed for graphic recording
purposes. The coils are mounted on
ball bearings and all restoring torque is
removed. The pivot shaft on one end
of the coil was extended and the vane
mounted directly on this shaft.

Potentiometer P2 is used for balancing
out any voltage generated by the
photocell dark current. Potentiometer
Pa adjusts the gain of the amplifier, i.e.,
the stiffness of the servoloop. It is

adjusted for good response without
overshoot. An Antihunt network is in-
cluded between the photocell load resis-
tor and the chopper. This materially
improves the transient response of the
servosystem. Constants are adjusted for
best performance of each amplifier.

The coil of the memory relay is con-
nected in parallel with the solenoid
which advances the exposure control
tape. Thus, the 0.22-juf condenser con-
nected to the relay contact holds its
charge and prevents the servosystem
from attempting to follow the operation
of the attenuator relays while the control
tape is being advanced. After the tape
has come to rest in its new position, the
memory relay closes and the condenser
assumes the new voltage established by
the relay-controlled attentuator.

In Fig. 6 is shown the circuit diagram
of the power supply. The high-voltage
supply is of the choke-input type so that
a 480-cycle signal can be picked off the
high-voltage rectifier by means of a
circuit tuned to the fourth harmonic of
the ripple frequency. This signal is
amplified and used to drive the six
choppers. Potentiometers across the 6.3-v
heater circuits and across the 12-v, 480-

414

November 1952 Journal of the SMPTE Vol. 59

TO NEC CONTACTOR

Fig. 6. Schematic circuit of power supply for servoamplifiers.

cycle output are adjusted for minimum
residual signal at the output of the am-
plifiers when the photocells are dark and
the outputs of the reference voltage po-
tentiometers are grounded. The ger-
manium and selenium diodes across the
relay coils are for contact spark suppres-
sion.

The filters associated with the photo-
cells have been chosen so that the
spectral sensitivity of the photocell as
modified by the filter matches approxi-
mately the spectral sensitivity of the
respective component of the color print
emulsion. For measuring the red ex-
posure, an SI photosurface and a Kodak
Wratten Filter No. 29 are used; for the
green, an S4 photosurface and Kodak
Wratten Filters Nos. 57A and 16 are
used; and for the blue, an S4 photo-
surface and Kodak Wratten Filters
Nos. 47 and 2B are used.

The same relatively sharp-cutting
filter combinations are used to filter
the three beams in the optical system
in order to provide a wide range of
control of color balance. If less selec-
tive filters were used, a given filter
might permit enough leakage of light
in an adjacent band so that the exposure

in that band could not, in extreme
cases, be reduced to a sufficiently low
value. This would only occur when
printing badly unbalanced negatives.
If experience proves that negatives are
relatively uniform in color balance, less
selective filters can be substituted in the
optical system, with a resulting increase
in the available overall exposure.

Performance

The normal operating speed of this
printer is 100 fpm. The lamp used is
a 1000-w, 120-v, T-12 prefocus lamp,
operating at 100 v. Under these condi-
tions there is a 0.6 log E margin in
exposure above that required from
printing a normal negative onto Eastman
Color Print Safety Film, Type 5381.
As first stated, the tape-controlled
exposure adjustment covers 0.62 log E
in 0.02 log E steps, or a total of 32 steps.
If the system is adjusted so that a normal
negative prints at Step 16, then there is
a range of ±0.30 log E available for over-
and underexposed negatives.

The lamphouse is cooled with a 200-
cfm blower and the air path through the
lamphouse and light baffles is designed
for a minimum of resistance so that the

J. G. Streiffert: Control for Color Printing

415

cooling of the lamp, lamphouse, and
condenser system is very effective. Also,
as mentioned, the lamp can be under-
voltaged by 17% with adequate margin
of exposure. Under these conditions it
is estimated that the lamp life should
be of the order of 200 hr. In a system
of this type with servocontrol of exposure,
there need be no concern regarding
blackening of the lamp or fluctuations
in line voltage. These factors affect
only the maximum available exposure.
Below this maximum, the exposure is
substantially independent of the lamp
voltage or its condition.

The response time of the servosystem
is about 0.02 sec. Thus, at a printing
speed of 100 fpm, the exposure change
is effected in one-half the frame height.

Because of the large vertical angle
between the three light beams, color

fringing will occur if there is poor con-
tact between the films. Thus, the
divergence between the colored beams
is, in a sense, an advantage in that it
gives a positive indication of poor printer
performance.

Discussion

Paul Ireland (EDL Company}: Is there
any provision for the calibration of this
to take care of drift in the photocell?

Mr. Streiffert: Not inherently in this
system. I have a photoelectric exposure-
measuring device which consists of a
bracket which I can screw in front of the
printing aperture and in which I can insert
photocells with appropriate filters — the
same filters which are used in the optical
system. That's connected to a vacuum
tube voltmeter and is used for checking
exposure from time to time to be sure that
it's constant.

416

November 1952 Journal of the SMPTE Vol. 59

Motion Picture Studio Lighting
and Process Photography Report

By JOHN W. BOYLE, Committee Chairman

J. HE BASIC COLOR sensitivity of the
Technicolor process has been changed
to a color temperature of 3350 K. When
white light sources, such as sunlight,
are used, the camera optical systems
are filtered for proper balance. In-
candescent tungsten filament lamps of
the proper color temperatures are used
unfiltered. When carbon arcs are used
mixed with unfiltered tungsten lamps
it becomes necessary to filter the carbon
arcs to the lower color temperature.
This is accomplished by using one
MT-2 and one Y-l filter on all high-
intensity arc spotlamps and one MT-2
filter only on Duarc flood lamps. It is
possible, however, to filter the camera
optical train for sunlight balance and
use the carbon-arc floodlamps un-
filtered, the high-intensity carbon-arc
spotlamps with only a Y-l light yellow
straw filter, and to filter the incandescent
lamps with whiterlite filters as in the
past. This gives the system a greater
latitude so it may be used with in-
candescent tungsten lamps alone, where
desired, at a key-light level as low as
150 ft-c; or with carbon arcs, or sun-
light, with a key-light level of 300 ft-c;
or with mixed lighting in either case
provided the light sources are all ad-

A report submitted on September 4, 1952
by the Committee's Chairman, John W.
Boyle, Director of Photography, 139| S.
Doheny Dr., Los Angeles 48, Calif.

justed to the balance of the particular
camera filter system.

With these changes a number of things
are being tried in efforts to simplify,
reduce costs and to improve the existing
lighting equipment situation.

Many sets are being illuminated
almost entirely, or entirely, with in-
candescent lamps. The 10-kw bulb has
again been brought into use (Fig. 1),
also the Type T-5 5-kw lamp, which was
not previously in favor because of re-
strictions as to beam spread and overall
dimensions, as compared to the Fresnel
type 5-kw units.1

On large sets the 22 5 -amp carbon-arc
"Brute" lamp, filtered to 3350 K,
has been used a great deal for long
throws and effect lighting.2

While the situation caused a drastic
change in lighting methods and equip-
ment, some studios are now exploring
the values of the new system on both a
3350 K and a white-light basis. In other
words, where they have a large set
with follow-spots, or where night ex-
teriors are to be photographed, they
merely change the filter arrangement in
the cameras and shoot on a white-light
basis.

Both Eastman and Ansco color nega-
tive films are balanced to white light
and therefore, with these systems carbon
arcs are used for "booster" lights outside
as well as for interiors. When in-

November 1952 Journal of the SMPTE Vol. 59

417

*• fl

° 2

fn £

418

November 1952 Journal of the SMPTE Vol. 59

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a ^

.60

John W. Boyle: Studio Lighting Report

419

Fig. 5. Set used in Desilu Productions "I Love Lucy."

420

November 1952 Journal of the SMPTE Vol. 59

Fig. 6. Set used in Desilu Productions "I Love Lucy."

John \V7Boyle: Studio Lighting Report

421

candescent lamps are used they are
equipped with whiterlite filters.

The Paramount Studio's engineering
department has developed a remote-
control lighting system for use with
incandescent lamps (Fig. 2).3 With
this system lightweight units, mounted
in various places, may be moved at
almost any angle, or the focus changed
by remote control from a master station.
The system was designed for use on a
circus picture where the lamps had to
be mounted on the tent poles; however,
it is being adjusted with the thought of
bringing studio lighting to an auto-
matically controlled operation insofar
as is possible. At the time of this
writing only the one studio has built
any of these motor-drive remote-con-
trolled units.

Several studios have rediscovered the
desirable qualities of diffuse lighting of
the "north sky light" type for certain
applications.4 It is indicated for general
fill-light, for supplementing more direc-
tional light on close shots, and overhead
on foliage where its diffuse distribution
creates a uniformity of illumination as
contrasted to the heavier shadow effects
produced by the Fresnel-lens type units.
For the same reason it is not suitable for
shadow effects.

While most of the studios have pro-
duced one or more of these "reflected -
light" units, Figs. 3 and 4 illustrate types
produced at the M-G-M and Columbia
studios. These units are lightweight,
are easily handled and rigged, are of a
simple cone-and-drum shape with in-
terior surfaces coated with flame re-
tardent white paint which has not dis-
colored under temperatures encountered
in use.

They are fitted with either one or two
bulbs from 750-w to 5-kw in size. At
present the housing diameters range from
24 to 60 in., but experimental models of
other sizes and shapes are being made.

Figures 5 and 6 illustrate sets used on
the Desilu Productions of "I Love Lucy"
which is photographed for television.

This work is of particular interest because
Karl Freund, the veteran Director of
Photography who is in charge of photog-
raphy of this show, has utilized his
wide knowledge of motion picture studio
lighting practice to produce "plane-
lighting" and modelling effects. Many
people have indicated that the use
of multiple cameras and restricted
economies would necessitate very flat
lighting but Freund has shown that the
judicious use of directional light is not
only possible, but is highly desirable.5

In spite of the trend toward economy
and simplicity of production a number
of epic pictures have been made in
which production values have been
stressed with spectacular sets and light-
ing techniques. The year 1952 will
probably be one where the more or less
mechanical, production-line type of
lighting will compete with the daring
effect lighting to determine if the latter
has the draw at the boxofHce which
many feel to be the case. One element
feels that the audiences do not know the
difference between the two and because
they do not know the difference, they
will not feel the difference; the other
element believes that spectacular lighting
makes spectacular pictures.

References

1. R. G. Linderman, G. W. Handley and
A. Rodgers, "Illumination in motion
picture production," Jour. SAfPE,
40: 333-367, June 1943.

2. W. W. Lozier and F. T- Bowditch,
"Carbon arcs for motion picture studio
lighting," Jour. SMPTE, 57: 551-558,
Dec. 1951.

3. Arthur Rowan, "Set lighting by remote
control," Am. Cinemat., 32: 444, Nov.
1951.

4. Leigh Allen, "Reflected light for color
photography," Am. Cinemat., 32: 446,
Nov. 1951.

5. Karl Freund, "Shooting live television
shows on film," SMPTE 72d Convention
Program, Oct. 7, 1952.

422

November 1952 Journal of the SMPTE Vol. 59

Film Dimensions Committee Report

By E. K. CARVER, Committee Chairman

JL HE REPORT that follows is much
longer than that which the Film Di-
mensions Committee ordinarily has given.
One reason is that it leads up to a dis-
cussion of progress toward international
standards, as information on this matter
has not been widespread through the
Society's ordinary channels of communi-
cation. Another reason for a lengthy
report is that we wish to discuss a situa-
tion concerning 16mm film, a field
wherein so many people are engaged
that they seldom get together in the
manner that happens with those who use
35mm film. Accordingly, the com-
mittee has sent out several circular letters
and desires to make a relatively long
public report in an effort to reach every-
one that may be interested.

A questionnaire was sent out in March,
1952, to some thirty manufacturers of
16mm film equipment, and the results
have been studied. It appears from
the replies to the questionnaire that we
have not sufficiently emphasized the fact
that the proposed change in standard
dimensions will not make the present
film narrower in width than the film
formerly used in cameras or other equip-
ment.

You will remember that the standards
are written to describe the film "im-
mediately after cutting and perforating."
Although it was very clear in the minds

Presented on October 8, 1952, at the
Society's Convention at Washington, D.G.,
by Dr. E. K. Carver, Kodak Park, Eastman
Kodak Co., Rochester 4, N.Y.

of those who wrote the early standards
that these standards referred to widths
at the time of slitting, nevertheless there
has been the tendency among equip-
ment manufacturers to interpret them
to mean the maximum and minimum
widths of film that would ever be en-
countered under any circumstances. The
manufacturers of equipment soon learned
by experience that film would often be
found considerably narrower than the
standards. This fact was properly inter-
preted to be due to the shrinkage of the
film. Whenever equipment manu-
facturers found film to be wider than the
standards, they assumed that the film
was improperly slit. They did not fully
realize that film swells at high humidity
and that film, even though properly slit,
might swell under high humidity condi-
tions so that its width would be greater
than standard.

One reason why this swelling effect
was not better known was because of
the rapidity of shrinkage which occurred
with the old type of high-shrink film.
As soon as the package was openecj (or
even before this in case it was not ade-
quately, hermetically sealed in a metal
container) the film started to lose residual
solvents and to shrink. This loss of
solvents was more rapid at high humidi-
ties. Under most circumstances, there-
fore, the increase in width due to ab-
sorption of moisture from the air was more
than counterbalanced by the decrease
in width caused by loss of solvents to
the air. For this reason it was rarely
found in practice that film would be

November 1952 Journal of the SMPTE Vol.59

423

wider than the original slit width and,
therefore, manufacturers of equipment
began to consider that the standards
represented the maximum that they
would ever encounter. There was a
tendency, therefore, to construct film
gates and other equipment so that they
would pass film with a width of 0.630 in.
(16.0 mm) but of no greater width.
They felt that any film which exceeded
this width must be nonstandard film.

During the past ten or fifteen years
film manufacturers have found means
to improve the shrinkage characteristics
of film and can be expected to make
further improvements. Severe condi-
tions which might cause the older type
of film to shrink about 1% would cause
the newer type of film to shrink only 0.2
to 0.4%. The present film often reaches
the camera with no shrinkage whatever.
There is not much difference, however,
between the amount of swell due to ab-
sorption of moisture that occurs with
the newer type of film and that which
formerly occurred with the older type of
film. It thus has become much more
common to find the newer type of film
wider than standard. Since much of the
equipment has been constructed so as not
to accept film with a width appreciably
greater than 0.630 in., complaints have
arisen that the film was slit too wide.

These complaints forced the film
manufacturers to change the setting of
their slitting knives from about the
middle of the standard tolerances down
to a point near the narrowest tolerances
allowed. Accidental variations in slit-
ting meant that some of the film was slit
narrower than the allowed tolerances
but no complaints were ever received
for that reason. Complaints were still
received, however, on film which ap-
peared to be too wide at high humidities.
The slitting knives were set still closer to
the bottom tolerance. This practically
eliminated complaints from film which
was too wide but did not introduce any
complaints or any difficulties from film
which was too narrow. This was true

even though a large fraction of the film
fell below the "standard" width.

An investigation was undertaken to
find out what the widths have formerly
been at the time the film was actually
used. Statistical studies were made on
many samples of film purchased on the
open market and of film at the end of its
useful life. Measurements were also
made in 16mm film exchanges of the
regular, professional distribution systems.
The various measurements showed clearly
that the newer type film even with a
reduced slitting width typically would
reach the customer with a greater width
than old type film. However, the
width was not great enough so that one
could expect any more trouble at high
humidities than have been previously
encountered.

The present attempt to change the
standard for slitting 16mm film, there-
fore, is merely an attempt to recognize
in a formal manner the changes which
the film manufacturers have been forced
to make in order to avoid complaints
and to give the customer film as near
the old width as possible. We call
this an effort to maintain the "status
quo," which is what the ultimate user
often needs.

The Film Dimensions Committee
is anxious to make sure that all of the
equipment manufacturers thoroughly
understand this problem. If these manu-
facturers were to misinterpret the new
standard and reduce the dimension of
film gates, then we would be in serious
trouble. Complaints of film jamming
would increase. Pressure would be put
on the manufacturers of film to reduce
the width of their film. Competition
would force some of them to do so, and
then there would be pressure put on
the standardizing bodies to reduce the
standard width again to conform to
the width actually in use. One change
would follow another, leading to chaos.

Three methods have been proposed
to revise the standard to take care of the
above problem. One of them was

424

November 1952 Journal of the SMPTE Vol. 59

simply to change the slitting dimensions,
i.e., the dimension A in the Standard,
from 0.629 in. ± .001 to 0.628 in. d=
.001. Objections were raised to this
method of changing the standard be
cause it was felt that many people
would consider that this meant a true
reduction in width of film as it is
used and would, therefore, reduce the
width of the projector gates, camera
gates, printer gates, etc., with the results
described above.

In order to avoid this difficulty, it was
proposed that the Standard for dimen-
sion A be written 0.6285 in. =b .0015.
This way of writing the dimension would
lay claim to the greatest width of the
previous standard, namely, 0.630 in.,
and yet would permit film manufacturers
to reduce their slitting width as much as
required so that their low-shrink film
would not exceed the width of the high-
shrink film as previously manufactured.
This idea was rejected because some mem-
bers of the Committee felt that it would
make it appear as if the change might be
intended to permit less accuracy in
slitting width than heretofore.

For the above reasons the Film Di-
mensions Committee finally agreed to
recommend two standards. The old
standard was to be kept the same as
previously except that an asterisk was to
be inserted above dimension A referring
to the statement "For low-shrink film
dimension A should be 0.628 in. ±
.001 and dimension E, 0.0355 in." A
definition for low-shrink film was in-
cluded in the standard. The above
method appeared to our Committee
to take care of the difficulty in a fairly
practical way, and this is the standard
that is being recommended to ASA.

On the 9th and 10th of June at a
meeting of Technical Committee No. 36
(Cinematography) of the International
Standards Organization (ISO) this mat-
ter was further discussed. The three
propositions as outlined above were placed
before the Committee. The members
of the Committee were unanimous in

agreeing that some actual change in
slitting should be adopted. The British
delegates were insistent that their stand-
ards body would never accept different
standards for high-shrink and low-
shrink film and that they could not ac-
cept the increase in tolerance. The
only one of the three proposals which
they would accept was the reduction in
the standard as outlined in the first of
the above propositions with an addi-
tional statement somewhat as follows:

"Experience shows that it is common
for film to expand when exposed to
high relative humidity. Allowance
should be made for this factor in equip-
ment design and in no case should the
equipment design fail to accommodate
a film width of 0.630 in., 16.00 mm."

Rather than see the matter deadlocked,
the American group as well as the
French and German groups agreed to
this modification. Most of us felt that
all three proposals were * identical in
actual content and that any one of them
would be satisfactory as an International
Standard although we still preferred
our own choice for the American Stand-
ards.

The actual standards covered by the
work of the Committee are: PH22.5,
16mm Double Perforation; PH22.12,
16mm Single Perforation; and PH22.93,
35mm Low-shrink Film. These have
been submitted by this Committee to
the Standards Committee of the Society.
It might be mentioned that the standards
for 35mm low-shrink film intended to be
used as camera raw stock do not call
for a narrowing of the width, nor for
other changes that seem quite logical
from the point of view of shrinkage
alone. The reason for this is that no
changes have been made, however
logical they may seem, without consult-
ing the people in the trade who are using
the film every day. This policy of
considering the needs of the user is very
desirable in simplifying the procedures
and in preventing what might possibly
be unnecessary or undesirable changes

E. K. Carver: Film Dimensions Report

425

Optics Committee Report

By RUDOLF KINGSLAKE, Committee Chairman

•L HE COMMITTEE has completed its
study of the Photometric Calibration
of Lens Apertures (published Oct. 1952
for 6-month trial and comment), the
final report being now in the hands of
the Standards Committee for further
action.

American Standard Z22.53-1946,
"Method of Determining the Resolving
Power of 16mm Motion Picture Pro-
jector Lenses," was submitted to the
Committee for revision. Three small
changes in wording were made which,
however, do not affect the fundamental

A report dated August 18, 1952, prepared
by Committee Chairman Rudolf Kings-
lake, Hawk-Eye Works, Eastman Kodak
Co., Rochester 4, N.Y., for presentation
on October 7, 1952, at the Society's
Convention at Washington, B.C.

procedure in any way. This Standard
has been approved by the Standards
Committee for reissue and is currently
being reviewed by ASA Sectional Com-
mittee PH22.

The next project to be undertaken
by the Optics Committee is an attempt
to standardize the physical dimensions
of motion picture projection lenses.
Tentative drawings have been issued
showing the proposed outline boundaries
between projector and lens, covering
two sizes of 16mm lenses and two (or
three) sizes of 8mm lenses. Copies
have been sent to all known manufac-
turers of 8mm and 16mm lenses and
projectors, and to members of the 1 6mm
and 8mm Motion Pictures Committee,
in the hope that a set of dimensions will
be reached which will be acceptable to
the whole industry.

426

November 1952 Journal of the SMPTE Vol. 59

American Standards —

PH22.83-1952, PH22.38-1952 and Z22.33-1941

IN OCTOBER 1952, the American Standards Association approved one new standard,
approved revision of a second standard and withdrawal of a third.

The new standard, PH22. 83-1 952, Edge Numbering 16mm Motion Picture
Film, was published for trial and comment in the January 1951 Journal.

Since the change in PH22.38-1952 (formerly 22.38-1944) was so minor, con-
sisting merely of the addition of a note, it was not considered necessary to publish
the proposed revision for a trial period. The above two standards are the product
of the 1 6mm and 8mm Motion Pictures Committee and are published on the follow-
ing pages.

Approval has been withdrawn from the ASA Recommended Practice, Z22.33-
1941, Nomenclature for Electrical Filters. This recommended practice was initiated
by the Motion Picture Research Council as an outgrowth of some work on theater
equipment. It was thought at the time that this method of designating electrical
filters would be helpful in the motion picture field. It was useful for a while but has
not been so for some time; therefore the SMPTE Sound Committee with the ap-
proval of the MPRC initiated withdrawal action about a year ago. — H. K.

Correction —

PH22.80-1950 and PH22.81-1950

AN ERROR has recently been discovered in two American Standards, Scanning Beam
Uniformity Test Film for 1 6-Millimeter Motion Picture Sound Reproducers (Labora-
tory Type), PH22.80-1950 and (Service Type), PH22.81-1950, approved in June
1950 and published in the July 1950 Journal. The sound track width was given as
0.070 inch instead of 0.072 inch.

These standards are now being reprinted by ASA and republished here on pages
430 and 431.

November 1952 Journal of the SMPTE VoL 59 427

American Standard

Edge-Numbering 16-Millimeter
Motion Picture Film

Kef. V. S. Pal. OS.

PH22.83-1952

•UDC 778.5

I. Purpose

1.1 The purpose of this standard is to establish a uniform practice with
respect to the interval between edge numbers when they are latent-image
printed on 16-mm raw stock film. It is not intended to imply that all 16-mrr
film should be edge-numbered.

2. Edge-Numbering Distance

2.1 The distance between consecutive numbers shall be 40 frames. Thus,
the numbers will indicate film footage, subject to a small correction for shrink-
age of the film.

Approved October 8. 1952. by the Am.riean Sfandardi Association. Incorporated
Sponsor: Society of Motion Picture and Television Engineers

•Universal Dccimi! Cltnificilion

428

November 1952 Journal of the SMPTE Vol. 59

American Standard

Raw Stock Cores for
16-Millimeter Motion Picture Film

Reg. V. S. Pat. Off.

PH22.38-1952

Revision of
Z22.38-I944

'UDC 778.5

Millimeters

Inches

25.90 ± 0.20

1.020 ±0.008

50.00 ± 0.25

1.968 ±0.0 10

15.50 ±0.50

0.610 ±0.020

Recommended Practice

16.70 ±0.30

0.657 ±0.01 2

4.00 ± 0.20

0.1 57 ±0.008

Bore A to fit freely to hub 25.40 ±0.1 mm or
1 .000 ± 0.004-inch diameter.

It is permissible to reduce the cross-sectional area and to provide a slot
in the periphery to facilitate starting the film on the core, so long as these
details do not interfere with the stated dimensions. Except for the slot and
keyway, the periphery and bore should present smooth, unbroken surfaces.

Approved October 8, 1952, by the American Standards Association, Incorporated
Sponsor: Society of Motion Picture and Television Engineers

November 1952 Journal of the SMPTE Vol. 59

429

American Standard

Scanning-Beam Uniformity Test Film for

1 6-Millimeter Motion Picture Sound Reproducers

(Laboratory Type)

Reg. U. S. Pal. Off.

Z22.80-1950

>UDC 778.534.4

1. Scope and Purpose

1.1 This standard describes a film which may
be used for determining the uniformity of
scanning-beam illumination in 16-mm mo-
tion picture sound reproducers. The recorded
sound track shall be suitable for use in labora-
tories and factories.

2. Test Film

2.1 The film shall be a print from an original
negative. It shall consist of a 1000-cycle, vari-
able-area recording at full modulation of the
0.005-inch width and shall be approximately
sinusoidal. The track shall move uniformly
0.067 inch from one edge of the scanned
area to the other as shown in Fig. 1 .

Fig. 1

2.2 The position of the sound track relative
to the ends of the light beam at any instant
shall be shown by a diagram appearing in the
picture area, the size and location of which
is shown in American Standard Location and
Size of Picture Aperture of 16-Millimeter Mo-
tion Picture Cameras, Z22.7-1950, or any
subsequent revision thereof approved by the
American Standards Association, Incorpo-
rated.

2.3 The scanned area shall comply with the
American Standard Sound Records and Scan-
ning Area of 16-Mm Sound Motion Picture
Prints, Z22.41-1946, and the film stock used
shall be cut and perforated in accordance
with American Standard Cutting and Perfo-
rating Dimensions for 16-Mm Sound Motion
Picture Negative and Positive Raw Stock,
Z22.12-1947, or any subsequent revisions
thereof approved by the American Standards
Association, Incorporated.

2.4 The length of this film shall be approxi-
mately 34 feet.

NOTE: A test film in accordance with this standard
is available from the Motion Picture Research Council
or. the Society of Motion Picture and Television
Engineers.

Appendix

(This Appendix is not a part of this American Standard.)

Before using the above test film it is rec-
ommended that correct placement of the scan-
ning beam be determined by means of buzz-
track test film as specified in American Stand-
ard Specification for Buzz-Track Test Film for
16-Mm Motion Picture Sound Reproducers,
Z22.57-1947, or any subsequent revision
thereof approved by the American Standards
Association, Incorporated.

The uniformity of scanning beam illumina-
tion may be measured by means of a db meter

connected to the output of the sound projec-
tor amplifier. The illumination of the scanning
beam should be adjusted according to the in-
structions furnished by the manufacturer and
the variation of the output as registered on
the db meter should be observed. The illumi-
nation is considered satisfactorily uniform
when the output reading as measured by the
meter is within ± 1 Vz db across the entire scan-
ning slit.

Approved June 12, 1950, by the American Standards Association, Incorporated
Sponsor: Society of Motion Picture and Television Engineers

430

November 1952 Journal of the SMPTE Vol. 59

American Standard

Scanning-Beam Uniformity Test Film for

16-Millimeter Motion Picture Sound Reproducers

(Service Type)

Rrf. V. S. Pat. Of.

Z22.81-1950

'UDC 778.534.4

1. Scope and Purpose

2. Test Film

0.072 in. — H «—

Fig. 1

2.2 The position of the sound track relative
to the ends of the light beam at any instant
shall be shown by a diagram appearing in
the picture area, the size and location of
which is shown in American Standard Loca-
tion and Size of Picture Aperture of 16-Milli-
meter Motion Picture Cameras, Z22.7-1950,
or any subsequent revision thereof approved
by the American Standards Association, In-
corporated.

2.3 The scanned area shall comply with
American Standard Sound Records and Scan-
ning Area of 16-Mm Sound Motion Picture
Prints, Z22.41-1946, and the film stock used
shall be cut and perforated in accordance
with American Standard Cutting and Perfo-
rating Dimensions for 16-Mm Sound Motion
Picture Negative and Positive Raw Stock,
Z22. 12-1 947, or any subsequent revisions
thereof approved by the American Standards
Association, Incorporated.

2.4 The length of this film shall be approxi-
mately 3]/2 feet.

NOTE: A test film in accordance with this standard
is available from the Motion Picture Research Council
or the Society of Motion Picture and Television
Engineers.

Appendix

(This Appendix is not a part of this American Standard.)

Before using the above test film it is rec-
ommended that correct placement of the scan-
ning beam be determined by means of buzz-
track test film as specified in American Stand-
ard Specification for Buzz-Track Test Film for
16-Mm Motion Picture Sound Reproducers,
222.57-1947, or any subsequent revision
thereof approved by the American Standards
Association, Incorporated.

The uniformity of scanning beam illumi-
nation may be measured by means of a db

meter connected to the output of the sound
projector amplifier. The illumination of the
scanning beam should be adjusted according
to the instructions furnished by the manufac-
turer and the variation of the output as regis-
tered on the db meter should be observed.
The illumination is considered satisfactorily
uniform when the output reading as measured
by the meter is within — 1 Vz db across the en-
tire scanning slit.

Approved June 12, 1950, by the American Standards Association, Incorporated

Sponsor: Society of Motion Picture and Television Engineers 'Universal Decimal classification

November 1952 Journal of the SMPTE Vol.59

431

72d Convention, October 6-10

This was a very large and successful con-
vention. We have not developed a whole
schedule of comparative statistics for recent
conventions and we doubt the prospects
of pay dirt in such a vein, for each con-
vention has possibilities and successes
peculiar to itself. Such a large and
successful convention was nicely fitting as
the last convention under Bill Kunzmann,
retiring Convention Vice-President. Joe
Aiken, as Program Chairman and Local
Arrangements Chairman, made the most
of the Society's going organization and
momentum to build a papers program and
he organized the multitude of local ar-
rangements for responsible help by the
many capable people in Washington who
contributed very generously to the Con-
vention.

A particularly identifiable aspect of the
Convention was the seven sessions which
comprised the International Symposiums
on High-Speed Photography which John
Waddell began to promote and develop
about a year and a half ago. The success
and the breadth of the Symposium were
almost entirely the result of John WaddelPs
work, with associates on the High-Speed
Photography Committee coming through
with papers and with Joe Aiken anxiously
watching and finally arranging the pro-
gram and meeting facilities for the roster
of papers as it rolled up to an unpre-
cedented volume.

Mrs. Nathan D. Golden and Mrs.
Joseph E. Aiken, cohostesses for the
Ladies' Program, prepared a unique
program which brought out 240 ladies
for events which included a tea and re-
ception by Mrs. Truman at the White
House, the Society's 72d Semiannual
Cocktail Hour, Banquet and Dance, a
luncheon at the Columbia Country Club,
an evening at the Academia of the Motion
Picture Association of America, and a tea
at the Greek Embassy.

Special arrangements were made by
Max Beard for about 1 30 visitors to attend
the session on Thursday Afternoon at the
Naval Ordnance Laboratory, White Oak,

Md. SMPTE members were welcomed
by R. D. Bennett, Technical Director of
the Laboratory, who explained the Labora-
tory's place in the defense program. The
Signal Corps Mobile Television System
brought the audience a view of certain
outlying areas by microwave relay and
television receivers. Shock waves in the
supersonic wind tunnel were demonstrated.

Hotel and transportation arrangements
were locally under Henry Fisher who
made arrangements especially helpful for
visitors from overseas and also facilitated
the extensive program arranged for the
ladies. Gerald J. Badgley was active in
membership promotion along with Ray
Gallo, Chairman of the Society's Member-
ship Committee. Jim Moses gave a
welcome assist as a Washington member
to Len Bidwell who came from Camden
for a customary stint of getting out a big
week's worth of Convention publicity.

Under Convention Vice-President
Kunzmann, convention registration was
organized for Washington by Keith B.
Lewis who had the assistance of Phil
Cowett, Fred Gerretson, Max Kerr, Jim
Moses, Bill Nagel and Howland Pike.
This was a real job considering that, along
with the tabulation of registration which
follows, also to be dispensed were tickets
for two luncheons, the banquet, the bus
trip to the Naval Ordnance Laboratory,
and theater passes and information. This
was the way registration for the technical
program went:

Weekly

Daily

Total

Monday

241

276

Tuesday

143

Wednesday

165

198

Thursday

—

129

Friday

—

114

Total

332

528

860

Projection service for the sessions was
organized by Carl Markwith with assistance
by William Hecht, Wilson E. Gill, Ralph
Grimes, William Youngs and Glen
Ornstine. They supplied 16mm and 35mm

432

equipment lor the technical sessions and
also met the demands of five pairs of con-
current sessions. Public address and
recording of discussion — of which there
was a good deal — was under the direction
of Jack Greenfield who had the assistance
of Robert Dickinson, Richard Simpson,
Mike Loria, and Ed Moore who was
most effective in stepping into a late
schedule for recording some high-speed
photography papers, with equipment sup-
plied by Wilson E. Gill.

Further refinements in the Society's
public address and recording equipment
may be forthcoming. Editorial Vice-
President-elect Norwood Simmons has
appointed the following committee to
study the equipment: George Lewin as
Chairman, Edwin A. Dickinson, Jack
Greenfield and Fred Whitney.

Motion pictures for the opening of
sessions were garnered and made into a
coordinated film program by John V.
Waller who was assisted by John E.
Horton, Jack McGullough and Emerson
Yorke. The roster included:

Jet Test, 16-B&W, Air Force

Timber & Totem Poles, 16-color, U.S. Dept.

of Agriculture
This Theatre & You, 16-B&W, Motion

Picture Assn.
Operation Greenhouse, 16-color, Atomic

Energy Com.

School for Dogs, 35-B&W, RKO
Screen Actor, 16-B&W, Motion Picture Assn.
Shining Rails, 16-color, Gen. Electric
Gambling, 16-B&W, Navy
Small Town Editor, 16-B&W, State Dept.
Shoemaker & The Hatter, 16-color, Mutual

Security Agcy.
Costume Designer, 16-B&W, Motion Picture

Assn.
Representative Instructional Films, 16mm

Maint., Various
Arch Against The Sky, 16-B&W, Gt. Lakes

Steel Corp.

Unlocking The Atom, 16-B&W, Universal
Let's Go To The Movies, 16-B&W, Motion

Picture Assn.

Tanglewood, 16-B&W, State Dept.
Screen Writer, 16-B&W, Motion Picture

Assn.

There were more persons than usual
from overseas, many of them coming for
the International Symposium on High-
Speed Photography (see photo). A high-
light of the Symposium was the High-
Speed Photography Luncheon on Wednes-
day noon when A. C. Keller spoke on
"The Economics of High-Speed Photog-
raphy" which is published elsewhere in
this Journal. John Waddell was master
of ceremonies to welcome an overflow
crowd in the luncheon hall. There were
several of the Society's officers and Gover-
nors at the High-Speed Luncheon. John
Frayne, Editorial Vice-President, spoke
briefly about the accomplishments of the
High-Speed Photography Committee and
assured the High-Speed photographers of
the Society's continuous policy to help
in every way possible, believing that the
interests and activities of high-speed will
be served well within the Society's organi-
zational structure which permits integrated
activity of varying but related interests and
which at the same time brings the benefits
of mutually sharing in facilities, overhead
and man-hour costs.

It was of some interest to note not only
at the High-Speed Luncheon but also at
the high-speed paper sessions that a sizable
fraction of those attending had registered
for the entire week and also that quite
a few persons shuttled between high-speed
and the concurrent session in order to hear
particular papers. This may or may not
be an indication of greater diversification
of high-speed people's interest, to include
phases of laboratory practice, optics or
sound.

The highest attendance at a session was
247 on Tuesday afternoon for Karl Freund's
paper "Shooting Live Television Shows on
Film." It was read by John Boyle in the
absence of the author who is currently on
a rigid four-days-a-week Hollywood tele-
vision schedule. The paper was tainted
with entertainment possibilities by showing
on a sizable screen a film of I Love Lucy
which demonstrated the cameraman's
problem.

The only other sessions to draw over
200 were two of the seven sessions of the
International Symposium on High-Speed
Photography. During the high-speed ses-
sions there was some filing in and out for
particular papers but, during the first two

433

Five of the world's foremost specialists on high-speed photography discuss pro-
gram for largest international symposium on the subject at the 72d Semiannual
Convention. Left to right: Dr. Hubert Schardin of Weil Am Rhein, Baden, Ger-
many, Director of the French Ordnance Laboratory at St. Louis, France, and world
authority on ballistics photography; Dr. Carl Jennergren, of the research staff of
the Swedish Ordnance Laboratory at Stockholm; W. D. Chesterman, of the Royal
Naval Scientific Service in London, author of the first English text on high-speed
photography; Gilbert Ruellan, Managing Director of the Andre Debrie Establish-
ment, French manufacturers of motion picture equipment; and Major P. Naslin,
of the research staff of the French Ordnance Laboratory of Vincennes, co-author of
the world's first text on high-speed photography, published in 1950.

days of high-speed, attendance held to an
average of 150. By Friday apparently
even the high-speed photographers' fibers
and capacities were taxed, for then at-
tendance averaged 80.

The Monday evening television session
and the Thursday evening 16mm main-
tenance sessions held the rapt attention
of about 80 throughout. Other sessions
not previously mentioned ranged from 125
to 175.

There were fourteen committee meetings
held during the Convention, many of them
lasting for several hours. Reports of these
appear in the Engineering Activities
column in this Journal.

The Luncheon and Banquet were
organized by Nate Golden who put them
on with a strict schedule. The awards

presented at the Banquet will be described
in the December Journal. Nate Golden
arranged for speakers from the three
service branches. Their remarks before
the Get-Together Luncheon were impres-
sive and warmly received. The speeches
are abstracted below. One of Joe Aiken's
special plans for this Convention was to
feature the Signal Corps Mobile Tele-
vision Unit. This and other television
plans were under Ralph N. Harmon and
Col. C. S. Stodter. W. P. Dutton was
most helpful in the planning but un-
fortunately was ill at Convention time.
The Get-Together Luncheon program
was picked up by the Signal Corps Mobile
Unit and sent to the Pentagon. The
program included speeches abstracted as
follows :

434

Ranking photographic authorities of the Army, Navy and Air Force confer with
Peter Mole (second from left), President of the Society of Motion Picture and Tele-
vision Engineers, on luncheon program opening the Society's 72d Semiannual
Convention at the Hotel Statler, Washington, D.C. The military experts, who were
guest speakers at the luncheon, are (left to right) Major General George I. Back,
Chief Signal Officer of the Army; Brig. Gen. Brooke E. Allen, Chief of Stan7 of the
Military Air Transport Service and, until recently, Commanding General of the
Air Photographic and Charting Service of the Air Force; and Capt. A. D. Fraser
Chief of Naval Photography in the Office of the Chief of Naval Operations.

Get-Together Luncheon Remarks by President Mole

A short time ago I had occasion to re-
view the history of engineering in the
motion picture industry, and I was re-
minded repeatedly of the mature judgment
and wisdom that our predecessors in this
Society had contributed to the progress
of motion picture technology. They
played an important part in the develop-
ment of sound and color motion pictures
and standardization, all of which are
commonplace today.

We are on the threshold of another era
of progress. I am sure we will all agree
that the movies and television can not
only live together but can supplement and
strengthen one another. The record of
cooperative engineering within our Society,
which extends across both fields, is already
an impressive one, and through such efforts
we have sounded a note of profound
encouragement for both the economic and

the technical future of the field in which
most of us make our daily living.

This week here in Washington, some of
our most distinguished members will be
discussing questions of serious importance
to the future of theater television. Last
week a significant event occurred when
Cinerama, a development many years in
the making, was first demonstrated to the
public in New York. The week before,
large-screen theater television enabled
thousands from coast to coast to witness
the championship bout between Rocky
Marciano and Jersey Joe Walcott. More
people saw the telecast in movie theaters
than were actually in attendance at the
fight. Now, none of us can predict in
exactly what direction theater television
will develop. Nor can we foretell the
future of Cinerama, or that of the several
new systems of motion picture color.

435

But one thing is certain — these technical
developments and the excitement they
have created, within and outside our field
of professional engineering, are together
the most encouraging symptoms to appear
in the past ten years. They are evidence
of a new, widespread, and healthy interest

Excerpts From Address by Gen. George I.

It is a distinct pleasure for me to join
with you at the opening session of your
72nd Semiannual Convention and to be
given the opportunity of presenting some
of my thoughts regarding motion pictures
and television within the Army.

Broadly speaking, the Signal Corps,
in keeping with its responsibility for pro-
viding an integrated communications sys-
tem for the Army, must be prepared to
transmit information (or what we call
intelligence), whatever its form may be.
This intelligence may be transmitted as
the spoken word, the written message, or
in the form of a pictorial representation.
It may be directed to a single person or
to several addressees at different places
throughout the world. It may also be
intended for mass distribution to thousands.

In the process of transmission, intelli-
gence may take many and varied forms
as it is transformed through electronic,
mechanical magnetic or photographic
processes. But whatever the processes em-
ployed, they must be designed to provide
a thoroughly integrated, but flexible, sys-
tem which will deliver the message ac-
curately and rapidly.

The motion picture has served the Army
well through two world wars. The sound
motion picture is doing the same important
job in the Korean conflict, as a medium
for training our forces, as a means for
promptly acquainting the American public
with our operations in combat, and finally
as a means of pictorially documenting
military history as it is written. Of
possible interest is the fact that seventy
million man-hours of military training are
accomplished annually by the Army
through the use of training films. Fur-
thermore, many of these films are exten-
sively used by our allies after the script
has been rescored in the appropriate
language, thus creating a unity of military
thinking and a better understanding of
mutual security problems. Similarly, in

in the technical future of both motion
pictures and television. I sincerely hope
they will spark a chain reaction that will
eventually stimulate each one of us,
working together in this Society, to accom-
plishments greater than any we have yet
attained.

Back

the field of research and development of
military equipment, methods and tactics,
the motion picture has become an irre-
placeable tool, since it provides a means
for repeated analytical study of critical
phases of a given operation, whether it
be a military maneuver or the testing of
such weapons as the atomic bomb or the
guided missile.

While military applications of the sound
film continue to multiply, television has
become available as another medium for
the transmission of sound and pictures, a
medium which offers tremendous possi-
bilities with its potential of speed and
accuracy. Although the full military
possibilities of television have not yet
been determined, we have for some time
been engaged in exploring its manifold
applications. In this work we have been
guided by our past experiences in the
pictorial communication field. Many
possible applications for military television
suggest themselves. To mention but a
few:

Distant tactical observation of military
positions and actions from the ground and
air.

Bringing distant or relatively inaccessible
subjects into many training classrooms
simultaneously.

The tactical briefing of widely separated
commanders.

Guidance and control of land vehicles
and light aircraft.

Close-up observation of the action and
effect of our weapons.

Mass dissemination of important in-
formation in pictorial form to reserve
and civilian components of the armed
services and to the public at large.

These are only a few of the suggested
fields of employment. I believe, how-
ever, that they indicate the trend of
military thinking toward full utilization
of this new method of communication.

436

Incidentally, the Signal Corps is pleased
to be able to bring to this convention the
Mobile Television System which is being
used in our fundamental explorations of
television's possible military applications.
This equipment embodies much of the
engineering skill which you engineers
have contributed to the development of
the television medium and emphasizes the
spirit of scientific cooperation that exists
between your industry and the Signal
Corps. Needless to say, we in the Army
are grateful to you for the splendid as-
sistance we are receiving from you.

I should like to point out here that the
Army has recognized the need for comple-
mentary development and utilization of
television and sound motion pictures in
order to obtain the maximum effectiveness
of both media, just as you engineers have
recognized that the two are complementary
and compatible, rather than exclusively
competitive. Only television can re-
produce an event at a distant point
instantly, but only motion pictures can

record and retain the image of that event.
By combining the electronic immediacy
of television with the photographic re-
tentiveness of the motion picture, we can
have available to us the maximum facility
possible in pictorial communication. For
this reason, the Army has placed the re-
sponsibility for development of both media
in the hands of the Signal Corps, thus
assuring full coordination in their develop-
ment.

In closing, I should like to appeal to
you for continued assistance and coopera-
tion in the research and development field
in both sound motion pictures and tele-
vision. This is essential if we are to
provide our combat forces with the best
that industry can produce. By that I mean
techniques and equipment which will
insure complete reliability under field
operating conditions, optimum perform-
ance characteristics consistent with the
state of the art, and reasonable cost under
conditions of mass production. Any lesser
goal will not be good enough.

Excerpts From Address by Gen. Brooke E. Allen

.... The Air Force is privileged to have
both in uniform and as civilians members
of your distinguished Society. The closer
our association with you the easier it will
be to accomplish our job for the Air Force.
Be assured that we fully appreciate the
accomplishments of the scientists, the
engineers and the technicians in your
field, and we gladly join ranks with you
and propose to do our full share toward
the advancement of the art.

When I received my invitation to speak
to you, I was in command of the Air
Photographic and Charting Service, which
constitutes one of the family of operational
services under the Military Air Transport
Service. Shortly thereafter I was trans-
ferred to my present position as Chief of
Staff of the Military Air Transport Service.

Since it was my responsibility to estab-
lish the Photographic Service, it is close
to my heart, and I could not possibly
forego a chance to explain its missions
and aims to you.

I should like to go back a bit in order
to get the record straight. Photography
since its inception has been vitally im-
portant to the military. Aerial photog-

raphy began to have meaning when
intelligence photographs were laboriously
taken from captive balloons in the war
between the states. A century ago, an
ingenious Frenchman made a map of
Paris on the basis of photographs taken
from a balloon. Out of that simple
beginning grew the science of military
photography.

The development of motion picture
photography has made it possible to
document photographically the live action
of the battlefield, on land, on the sea and
in the air. The vital military importance
of such a photographic record is obvious,
just as every football coach insists on a
motion picture record of Saturday's game
for Monday's critique.

Under the Unification Act of 1947, the
Department of the Air Force was given
complete responsibility for its own photo-
graphic functions. This did not, however,
result in the automatic establishment of a
satisfactory organization to perform those
functions.

Instead, the photographic responsi-
bility became scattered among the major
air commands without overall control,

437

supervision or coordination. This was
simply one of the growing pains connected
with the establishment of the Air Force
as a separate Department along with the
Army and the Navy.

It was not strange, therefore, that the
outbreak of hostilities in Korea found the
Air Force unprepared to meet its photo-
graphic requirements in an efficient and
organized manner. The Army and the
Navy, on the other hand, were well pre-
pared to document their combat activities
with photography, so essential for opera-
tional purposes. When the Chief of Staff
of the Air Force became aware of the
situation, he directed the immediate
establishment of a photographic service
to satisfy the most urgent requirements of
the Air Force.

After almost a year of careful study and
planning, the scattered but related ac-
tivities of the Air Force were reorganized
under a single command, which was
designated the Air Photographic and
Charting Service. The principal elements
of the Photographic Service are:

The Photographic Documentation
Group ;

The USAF Photographic Center;

The Mapping and Charting Group ; and

The Aeronautical Chart and Informa-
tion Center.

The units of these activities are of
necessity scattered from Korea through
Europe, to North Africa and the Middle
East. Wherever the global mission of the
Air Force requires its operation, there
also you will find units of the Air Photo-
graphic and Charting Service.

I should like to emphasize that during
the year in which the Photographic Service
was being organized and firmly established,
photography did not stand still. During
that first year our Combat Camera Unit
in Korea piled up over 300 combat mis-
sions and exposed more than 225,000 feet
of motion picture film in combat. The
Unit ran up an outstanding record of
awards and decorations and took their
combat losses along with the fighting units.

Today we are happy to fall in step with
the pace set by you television engineers.
We have brought the field of electronics
into a firm position in our organization.
Indicative of how we are accomplishing
this in the Photographic Service is the

fact that the production division has a
split title. It is called the Motion Picture
and Video Production Division. In this
Division we have affected a marriage of
these two fields without any of the initial
rivalry that ran through industry when the
motion picture and the television people
first eyed each other warily from opposite
sides of the fence.

It was a matter of firm pride to think
that I was connected with the creation of a
video production unit in the Air Photo-
graphic and Charting Service. The
mission of this unit is built around the
high-speed concept, completely mobile
with the latest electronic equipment. This
unit is now undergoing the equipping phase
prior to an operational shakedown.

It was established on an experimental
basis to ascertain as early as practicable
the applicability of television to the
operational and training mission of the
Air Force. Part of their portable equip-
ment is a 16mm rapid processor which was
first presented, I believe to the Society
at your convention in Chicago in April
1950. As you know, this machine presents
a ready-to-project print beginning ninety
seconds after initial photography.

As the author of any new work takes
great pride in crediting his source material,
we do so with a bow of great appreciation
to industry and to our elder services — the
Army and Navy. Throughout all of our
efforts, we have maintained liaison with
industry, with the experiments conducted
by the universities and colleges throughout
the country and the work done by the
Navy in its Special Devices Center at
Sands Point and, of course, with the
Army's "Operation Caravan."

No great degree of imagination is re-
quired to see unlimited possibilities in the
application of TV to technical, flight and
combat crew training, and through kine-
scope recordings the preparation of train-
ing films with celerity and informality
hitherto impossible. What we lose in
artistry, we gain in speed and volume.

I have given you a rough sketch — yes-
terday, today and tomorrow — of photog-
raphy and television in the Air Force.
Your meeting here in Washington seems
to key note high-speed. In the Air Force
we are trying to keep our thinking and
our planning in that same key — to keep
the pace that you are setting.

438

In discharging its global mission in
photography and television, the Air Force
is seeking every means to get information
faster and better and to put it to its maxi-
mum use in the shortest time. As you
television engineers know the television
circuit can be the shortest and speediest
route from live action to finished film.
This is of major importance to us today.
As you engineers come up with new
methods, new techniques, faster and
better ways to accomplish our mission,

you can be sure that the Air Force matches
your zeal with our own desire. We are
proud to serve with you in the search for
better ways of getting the job done.

It is a constant but exciting challenge.
We are happy to be able to join you in it.
As for the future, the course seems clear
ahead of us. To coin a phrase, we have
now become airborne and over our first
and most difficult obstacles. As for the
rest, the horizons are unlimited.

Excerpts From Address by Capt. A. D. Frazer

.... In the Navy, we use motion pictures
extensively and the requirements for the
use of television are continually expanding.

Entertainment motion pictures provide
probably our greatest morale booster.
Every ship and station has movies and I
can tell you from personal experience that
when the movies do not arrive or they
cannot be shown for some reason the boys
are very unhappy. We are, of course,
dependent on the motion picture industry
for these films and are deeply appreciative
of the service provided and the technical
improvements that have been made to
give us better sound and color for the
adverse conditions encountered in ship-
board screenings.

In our military use of motion pictures,
the largest single requirement is in the
field of training films. We also use them
extensively for test and evaluation of new
equipment. This is especially true in
the guided missile program where high-
speed motion picture photography has
become most valuable.

Recording of Naval operations for
historical purposes and evaluation is of
great importance. There is a growing
need for motion pictures in combat briefing.

Boat crews that have to approach a
hostile beach during an amphibious opera-
tion can learn a great deal from seeing
movies of the beach area made previously.

[Capt. Frazer spoke briefly of the Navy's
training film program — this was described
in detail by Cronenwett and Timmons in
the July 1952 Journal.]

In the development and test of new
equipment, motion pictures have proven
to be invaluable. This has been par-
ticularly true in the evaluation of equip-

ment that operates faster than the eye
can follow or the mind record. A few
examples are:

Wind tunnel tests of sonic and trans-
sonic airfoils;

Instrument recordings of tests of new
aircraft ;

Recording of instrument readings of
tele-metered flights of guided missiles;

Determination of explosion;

Phenomena of new types of weapons
and explosives and their effect on naval
equipment; and

Verification of proper sequence and
operation of a series of functions in various
mechanical and electrical devices.

Many of these uses will be discussed in
detail in later sessions of your Convention.

On our larger ships, and especially in
aircraft carriers, we have motion picture
camera equipment for recording various
aspects of naval operations. These are
used for historical recording, and for study
to improve the execution of various
maneuvers and to detect deficiencies in
equipment.

Training in the basic techniques of
motion picture photography is given to
all students at the Navy's photo school at
Pensacola, Florida. A specialized course
at the same location is also conducted for
a limited number of advanced students.

The motion picture industry in Holly-
wood very generously operates a compre-
hensive on-the-job training course for
selected personnel. This program has
proven to be most beneficial and provides
a phase and completeness of instruction
that is not possible of attainment in a
service school.

In the field of television, the Navy has

439

been active in development work since
before World War II. Television control
of drone aircraft was successfully demon-
strated and used in the South Pacific by
the Navy in 1944. More recently, as
reported in the press, it has been used
successfully in Korea.

The employment of television for Naval
purposes opens many new possibilities.
Improvement in the equipment will,
however, be necessary. Needed are
further reduction in size and weight of
camera and transmitting equipment, and
considerable improvement in reliability
under very adverse operating conditions
with substantial increase in reception
distance. These requirements sound some-
what contradictory but I am confident
that the industry can solve the problems.

Photo recording of television and
cathode-ray tube images has been carried
out in the Navy for some time. This
utilization has progressed to the point
where much of the work is done auto-
matically. There is still room for progress,
however, in the development of new and
more sensitive emulsions and more rapid
processing of these emulsions. Results
obtained along these lines, to date, have
been very gratifying. In the field of group

instruction, television has been used
experimentally and the Navy Special
Devices Center is continuing study of this
medium. Test instruction has been quite
satisfactory and indicated a good per-
centage retention of transmitted informa-
tion. Closed circuit, broadcast, and kine-
scope methods have been used in this
program. The feasibility of using this
system for briefing purposes and group
instruction within task forces at sea is under
development for evaluation.

The uses of television in the testing and
examination of devices and equipment for
naval employment are almost limitless.
Small television cameras can be placed
within equipment where it is physically
impossible for a human observer to be
under such conditions as: limitations of
space, atmospheric conditions, high G
forces, high temperatures, or severe vibra-
tion. There are many more.

The Navy is vitally interested in new
developments in the field of television and
motion pictures. Their parallel use holds
great promise for the future. We look
to the Society of Motion Picture and
Television Engineers for future develop-
ments that will make past successes seem
insignificant by comparison.

Engineering Activities

72d Convention Thirteen Engineering
Committees held meet-
ings at the 72d Convention in Washington,
B.C., October 6-10. This in itself made
for lively, efficient meetings. The schedule
was tight and required the use of mornings,
afternoons and evenings — including the
"morning after" the Wednesday night
banquet. On several occasions there
was hardly time for the chairs to cool as
one meeting adjourned and another was
called to order. The meetings successfully
furthered standards activity and provided
opportunities for the exchange of "shop"
talk.

Standards activity is at a very high level
today. In addition to the development
of new standards required by growth and
changes in the industry, the Society is in
the process of actively reviewing (in ac-
cordance with ASA rules) all standards

currently over three years old. The high-
lights of this activity as discussed in the
various committee meetings will be pre-
sented below and also in the December
Journal.

Film Dimensions Dr. E. K. Carver,
Chairman, was unable

to be present and his alternate, Dr. A. C.
Robertson, chaired the meeting. The
status of active projects was reported as
follows :

PH22.1, Alternate Standards for Positive
or Negative 35mm Raw Stock Film —
This proposal was published for trial in
the September 1951 Journal, approved by
the Standards Committee in July 1952,
by ASA Sectional Committee PH22 and
SMPTE Board of Governors in October
1952 and is presently betore the Photo-
graphic Standards Correlating Committee.

440

The following three standards (two re-
vised standards and a new proposal) were
approved by the Film Dimensions Com-
mittee and are now being reviewed by
the Standards Committee.
PH22.5, Dimensions of 16mm Silent

Motion Picture Film,
PH22.12, Dimensions of 16mm Sound

Motion Picture Film, and
PH22.93, Dimensions of 35mm Low

Shrink Camera Raw Stock Film

The periodic review of standards has
brought four standards up for consideration
and it was agreed that three should be
revised :

Z22. 17-1 947, 8mm Film Dimensions,
Z22.31-1946, Definition for Safety Film,
Z22.36-1947, 35mm Positive Film Di-
mensions ;
and the fourth reaffirmed:

Z22.37, 1944, 35mm Raw Stock Cores.

Film Projection This committee is simi-
Practice larly reviewing four

standards and here it
was also agreed that one should be re-
affirmed :

Z22.4-1941, 35mm Projection Reels;
and three revised:

Z22.29-1946, Projection Rooms and
Lenses,

Z22.35-1947, 35mm Sprockets, and

Z22. 58-1 947, 35mm Projector Aperture.

In addition several dormant projects,
"Projection Room Plans," and "Arc-Lamp
Mounting Dimensions," were discussed
and plans made to reactivate them.
Finally, the desirability of standardizing
the Society Leader from both a television
and a theater point of view was mentioned
and initial action in that direction
approved.

Films for This committee was largely
Television responsible for the develop-
ment of the Television Test
Film. Much thought was given at this
meeting to ways and means of further
improving it and changes may be expected
in the near future.

Standardization of the Society Leader
was discussed at this meeting also. As was
mentioned in the May 1951 Journal, this
leader was developed by the Leader Sub-
committee, chaired by Charles Townsend.

It was designed to keep the basic features
of the Academy Leader required by the
theater projectionists while adding useful
information required in projecting films
for television. The Subcommittee was
now asked to revise paragraph 3 of the
Release Print Standard, Z22. 55-1947, to
incorporate use of this new all-purpose
leader.

Laboratory Some half dozen standards
Practice are being reviewed by this

committee but discussion
on them was tabled until returns on the
letter ballot, issued a few weeks before
the meeting, are more complete.

Instead the discussion revolved about
two projects which have occupied the
committee's attention for some time:
( 1 ) Screen Brightness in 1 6mm Laboratory
Review Rooms; and (2) Printer Light
Change Cueing. No fundamental differ-
ences exist about the latter and agreement
was readily reached on a second draft
soon to be circulated to the committee.
Quite the converse is true of the former.
Here there are two schools of thought,
one holding that 16mm and 35mm screen
brightness should be the same (9-14 ft-L)
and the other arguing for a lower value
(5-10 ft-L) in 16mm review rooms. The
final decision was to issue a second letter
ballot, this time setting forth the arguments
for both positions and allowing for a choice
of either set of values.

Screen The 16mm review room

Brightness screen brightness proposal
was also discussed here and
with similar views expressed. This com-
mittee will receive the same letter ballot
prepared for the LP Committee.

The Subcommittee on Instruments and
Procedures submitted a final report of its
findings. This was approved for Journal
publication with but minor editorial
changes.

Wallace Lozier, Chairman, reported on
the status of the revision of the Screen
Brightness Standard, PH22.39. This has
run the gamut of approval within the
SMPTE, was published in the May 1952
Journal for trial (no adverse comment was
received) and is presently being reviewed
by ASA Sectional Committee PH22 —
Henry Kogel, Staff Engineer.

441

New Members

The following members have been added to the Society's rolls since those last published. The des-
ignations of grades are the same as those used in the 1952 MEMBERSHIP DIRECTORY.
Honorary (H) Fellow (F) Active (M) Associate (A) Student (S)

Bader, David A., Writer, Journalist, Literary
Associates. Mail: 147-66 Village Rd.,
Jamaica 35, N.Y. (A)

Ball, Howard D., Film Projectionist, Kennedy
Broadcasting Co. Mail: Box 87, La Jolla,
Calif. (A)

Del Rosario, Macario T., M/Sgt., U.S. Army,
Qtrs. 111-G-l, Governors Island, New York 4,
N.Y. (A)

Ellington, Frederick K., Theatre Circuit Main-
tenance Supervisor, Syndicate Theatres, Inc.,
Crump Theatre, Columbus, Ind. (A)

Epstein, Sidney, Electronic Engineer, S.O.S.
Cinema Supply Co. Mail: 111 Tudor PL,
Bronx 52, N.Y. (A)

Hathaway, Henry R., Jr., Officer in Charge of
Sound Recording Dept., U.S. Air Force.
Mail: 1027 Columbia Dr., Bucknell Manor,
Alexandria, Va. (A)

Heathcote, Bruce, SRT-TV Studios. Mail:
45-36 — 49 St., Woodside 77, N.Y. (S)

Henderson, John E., Projection Room Super-
visor, Jefferson Standard Broadcasting Co.
Mail: Sardis Rd., Charlotte, N.C. (M)

M aloof, Michael B., Jr., Audio Control Engi-
neer, Paramount Television Productions.
Mail: 1155 N. Heliotrope Dr., Los Angeles
29, Calif. (A)

Minor, M. J., Radio Engineer, Jefferson Stand-
ard Broadcasting Co., 508 Wilder Bldg.,
Charlotte, N.C. (M)

Navon, M., Director, Geva Films, Ltd., 32
Allenby Rd., Tel Aviv, Israel. (A)

Norling, Richard V., Motion Picture Tech-
nician, Byron, Inc. Mail: 12119 Edgemont
St., Silver Spring, Md. (A)

Seitz, Henry J., TV Film Transmission, Colum-
bia Broadcasting System. Mail: 89-18
Rutledge Ave., Glendale, L.I., N.Y. (A)

Sykes, Langthorne, Electronic Scientist, U.S.
Naval Ordnance Test Station. Mail: P.O.
Box 455, China Lake, Calif. (A)

Teitelbaum, Ben, Partner, Hollywood Film Co.,
5446 Carlton Way, Hollywood 27, Calif. (A)

Teitelbaum, Harry, Partner, Hollywood Film
Co., 5446 Carlton Way, Hollywood 27. (A)

Todd, Clayton S., Engineer, Metro-Goldwyn-
Mayer Studio. Mail: 3354 Mills Ave.,
La Crescenta, Calif. (A)

Tyo, John H., Audio- Visual Center, Indiana
University, Bloomington, Ind. (S)

Wallis, Gilbert, Project Engineer, Land-Air,
Inc. Mail: 405 Deney La., Alamogordo,
N.M. (A)

Zale, Ben, Editor, Industrial Photography,
1114 First Ave., New York 21, N.Y. (A)

CHANGES IN GRADE

Hu, Tsu-Ming, (S) to (A)
Stevenson, Murray H., (A) to (M)
Watermeyer, Erwin, (A) to (M)

DECEASED

D' Andrea, Matthew J., Free-Lance Technician.

Mail: 18 Hudson Ave., Edgewater, N.J.

(M)
Levinson, Nathan, Sound Director, Warner

Brothers Pictures, Inc., Burbank, Calif. (F)
Pariseau, S. M., District Manager, Altec Service

Corp. Mail: 1956 S. Vermont Ave., Los

Angeles 7, Calif. (A)

Meetings

Society of Motion Picture and Television Engineers, Central Section Meeting (in con-
junction with Society of Photographic Engineers), Dec. 3, Bell & Howell Co., Chicago,

111.

American Institute of Chemical Engineers, Annual Meeting, Dec. 7-10, Cleveland, Ohio

American Institute of Electrical Engineers (Symposium on The Science of Music and Its

Reproduction — 2d Lecture), Dec. 11, Engineering Societies Bldg., New York, N. Y.

American Society of Photogrammetry, Annual Meeting, Jan. 14-16, Shoreham Hotel,

Washington, D. C.

American Institute of Electrical Engineers (Symposium on the Science of Music and Its

Reproduction — 3d Lecture), Jan. 15, Engineering Societies Bldg., New York, N. Y.

Society of Motion Picture and Television Engineers, Southwest Subsection Meeting,

Jan. 16, Dallas, Tex.

American Institute of Electrical Engineers, Winter General Meeting, Jan. 19-23, New

York, N. Y.

442

American Physical Society, Annual Meeting, Jan. 22-24, Cambridge, Mass.
Institute of Radio Engineers Conference and Electronics Show, 5th Annual Southwestern

Conference and Show, Feb. 5-7, San Antonio, Tex.

American Institute of Electrical Engineers (Symposium on the Science of Music and Its

Reproduction — 4th Lecture), Feb. 20, Engineering Societies Bldg., New York, N. Y.

National Electrical Manufacturers Association, Mar. 9-12, Edgewater Beach Hotel,

Chicago, 111.

Society of Motion Picture and Television Engineers, Southwest Subsection Meeting

Mar. 16, Fort Worth, Tex.

Inter-Society Color Council, Annual Meeting, Mar. 18, Hotel Statler, New York, N. Y.
Optical Society of America, Mar. 19-21, Hotel Statler, New York, N.Y.
American Physical Society, Joint Meeting with APS Southeastern Section, Mar. 26-28,

Duke University, Durham, N.C.

American Physical Society, Apr. 30-May 2, Washington, D.C.
Acoustical Society of America, May 7-9, Hotel Warwick, Philadelphia, Pa.
Society of Motion Picture and Television Engineers, Southwest Subsection Meeting,

May 20, Dallas, Tex.

American Physical Society, June 18-20, Rochester, N.Y.

American Institute of Electrical Engineers, Summer General Meeting, June 29- July 3,

Atlantic City, N.J.

Biological Photographic Association, 23d Annual Meeting, Aug. 31-Sept. 3, Hotel Statler,

Los Angeles, Calif.

The Royal Photographic Society's Centenary, International Conference on the Science
and Applications of Photography, Sept. 19-25, London, England

Theatre Equipment and Supply Manufacturers' Association Convention (in conjunction
with Theatre Equipment Dealers' Association and Theatre Owners of America),

Oct. 31 -Nov. 4, Conrad Hilton Hotel, Chicago, 111.

Theatre Owners of America, Annual Convention and Trade Show, Nov. 1-5, Chicago, 111.
National Electrical Manufacturers Association, Nov. 9-12, Haddon Hall Hotel, Atlantic

City, N.J.

Employment Service

Positions Wanted

Audio-Visual School of Education Gradu-
ate: M.A., Audio- Visual Education,
New York University. Sound background
in personnel and contact work, attractive,
single, personable. Prefer position New
York or New Jersey area. Spent 3 years
abroad, civilian, Special Services Director.
Miss Fredericka Appleby, 810 Broadway,
Newark, N.J. HUmboldt 5-4582.

TV Producer-Director: Formerly Chief
of Production in Army's first mobile TV
system, experience in writing-directing
high-speed, low-cost instructional pro-
ductions; TV producer-director, KRON-
TV San Francisco, five shows weekly.
Desire connection in educational TV,
preferably employing kinescope technique;
married; prefer West Coast, but willing
to travel; resume, script samples, pictures
of work — on request. Robert Lownsbery,
1116 E. Claremont St., Pasadena 6, Calif.

Research, field engineering, manufac-
turing opportunity for B.S. Electrical
Engineering candidate, Jan. 1953; Scholar-
ship student, M.I.T. ; studied in Germany,
1945-1950. Languages: German, Polish,
Russian and English. Some radio shop
experience; also M.I.T. Library and
Engineering Dept. Single, no dependents;
Military Status, 5 A (over 26). Prefer
location in East. Joseph Liebermann,
513 Beacon St., Boston, Mass.

Position Available

Wanted: Young engineer, mechanical
or electrical deg; with liking for fine
machinery and creating it, some experience
in mechanical design and some knowledge
of optics or electronics; for work on
development of new products; applica-
tions held in full confidence. Send com-
plete resume to Sherman Fairchild and
Assoc., Rm 4628, 30 Rockefeller Plaza,
New York, Attn: Mr. Fairbanks.

443

New Products

Portable microphone boom, for studio or
location work, has been made of aluminum
tubing and bronze castings. It telescopes
approximately 7 to 17 ft, has a balance
weight at the rear of the boom that is
adjustable for extension, and has a remote
control allowing 360° rotation of the
microphone by a universal angular control

The Photovolt Densitometer, a

product of Photovolt Corp., 95
Madison Ave., New York 16, is
a combination of a Model 520-A
Multiplier Photometer, a Model 52
light source unit and a special guide
attachment for 35mm and 16mm
film strips. It is designed to measure
color (and black-and-white) densi-
ties in very small spots in the image
area as well as in ordinary and
silver sulfide sound tracks. It is
equipped also to read densities on
sensitometric tablets.

from the back. The boom dolly is a two-
section telescoping unit with collapsible
legs and ball bearing casters, with foot
locks. The boom complete with stand
collapses for portability and weighs about
100 Ib. Further details are available from
National Cine Equipment Inc., 209 W.
48 St., New York 19, N.Y.

SMPTE Officers and Committees: The roster of Society Officers and the
Committee Chairmen and Members were published in the April Journal.

444

The Electronic Camera
in Film-Making

By NORMAN COLLINS and T. C. MACNAMARA

The paper considers the cinematograph camera and assesses its inherent
limitations. The advantages of multiple-camera working are discussed, with
special reference to the electronic camera; the recording of an electronic
image is shown to be the culminating development. The paper discusses pic-
ture quality, contrast range and tonal fidelity, and the objective and subjective
evaluation of definition. The reconciliation of the electronic and photographic
viewpoints is shown to be possible, and the standards of the motion-picture
and television industries are compared. The paper concludes with a survey
of the performance requirements of the electronic camera, the mechanics of
motion-picture recording of electronic images and factors governing the choice
of film stock.

(1) Introduction

UP TO THE PRESENT, the history of film-
making has been virtually the history of
the cinematograph camera as it was con-
ceived by Friese-Greene and Lumiere.
Technical progress in design and de-
velopment has been constant, but it has
been in the direction of improvement and
refinement rather than the establishment
of new principles.

It is the intention in the paper to show
why there is reason to believe that a

Presented at The Institution of Electrical
Engineers Convention on the British Con-
tribution to Television, April 28-May 3,
1952, by Norman Collins and T. C. Mac-
namara, High-Definition Films, Ltd., 25
Catherine St., Aldwych, W.C. 2, England;
reprinted from J. Inst. Elec. Engrs. (London),
99, Part III A, No. 20: 673-679, 1952.

change may be impending, and why elec-
tronic cameras, with the vastly greater
measure of operational flexibility that
they can offer, may supersede the purely
optical camera as the basic instrument of
film production.

To substantiate such a view, the conse-
quences of which would inevitably mean
the introduction of far-reaching changes
in film-production technique, it is neces-
sary first to examine the characteristics of
the traditional optical-mechanical instru-
ment and then to determine how far those
characteristics have themselves governed
the technique. Secondly, it is relevant
to consider why any instrument possess-
ing what, in the view of the authors, are
inherent limitations in its application
should for so long have been accepted as
the standard apparatus of the industry.

It is not suggested that the modern

December 1952 Journal of the SMPTE Vol. 59

445

cinematograph camera bears more than
superficial filial resemblance to the
"magic boxes" of film-history. Indeed,
the current models of orthodox equip-
ment are elaborate instruments built to
precision-engineering standards and mod-
ified in every detail by half a century of
operational experience. In the result,
there has been evolved a piece of appa-
ratus of known and highly efficient opti-
cal characteristics, proved reliability in
performance and general simplicity of
maintenance.

Nevertheless, its basic principles re-
main unaltered. It persists as essentially
an instrument to record a sufficiently
rapid succession of single images of suc-
cessive stages of movement within the
framework of a single scene for the eye to
be deceived by the illusion of continuous
movement when the recorded images are
subsequently projected. If a visual suc-
cession showing two different views of the
same scene (as in a "cut" from a medium
shot to a close-up), or two views of en-
tirely different scenes (as in a cut from an
interior to an exterior), is required the
camera must occupy two different shoot-
ing positions, and the resultant film re-
cordings must be joined together before
the effect of the visual succession can be
artistically evaluated. Furthermore, if
the image of one scene is to be super-
imposed upon another (as in a "mix") it
is necessary to go beyond the resources of
the camera altogether and make use of
the additional optical processes of the
laboratory. In short, the single optical
camera by its nature has to be assisted
artificially before it can provide the mul-
tiplicity of recorded impressions from
different viewpoints that the modern
entertainment film requires.

Moreover, by its nature the optical
camera is secretive in operation and reti-
cent about its viewpoint until the exposed
film has been developed. At most the
camera shares its view with the camera
operator; others — the director, for in-
stance — may examine the scene in the
view-finder before "shooting" begins, but

in the result the utmost that can then be
said with confidence is that the image
appeared thus at the time of the exami-
nation and is not by any means how the
image will necessarily appear when the
camera actually begins operation. The
significance of this should not be over-
looked, for it means that, at the moment
of shooting, the director is inevitably ex-
cluded; he becomes, as it were, an on-
looker.

It is not, indeed, until after the de-
velopment and projection of the "rushes"
that the director is in any position to
know whether or not he has achieved the
original artistic purpose which lay be-
hind the "shot." And it is because of
this inability to pronounce judgment at
the time that the prudent director often
covers his misgivings by one or more
"re-takes," in order to ensure that some
part of the exposed film depicts the action
as he wishes it.

It is sometimes argued that the un-
avoidable period of waiting before being
able to study the projected film is not in-
jurious to the end-product but is, in fact,
positively beneficial. The view has been
expressed that the technical perfection of
the finished film can be obtained only by
these two distinct processes — the totally
undistracted shooting of individual and
unrelated scenes in the studio, followed
by the far more leisurely assessment of the
"rushes" when they are projected upon
the screen in the viewing theatre.

Such a view may well rest upon a con-
fusion of cause and effect, and may in-
deed conceal a misconception of proper
artistic method, for it can be argued
that, with the facilities offered by the
present type of camera, no other pro-
cedure could possibly be employed.

It now becomes profitable to consider
the relationship of the individual shots to
each other. It will be accepted by most
film-makers that a great — possibly the
greater — part of the artistic merit of the
finished film, i.e. its effect upon the audi-
ence, will ultimately depend as much
upon the juxtaposition of sequences as

446

December 1952 Journal of the SMPTE Vol. 59

upon the merits of the individual shots
themselves.

In film-making under present con-
ditions, however, the director is denied
the possibility of any prior judgment on
this point. He is compelled to rely upon
"assembly" or "rough-cut" of the rushes
before he can begin to evaluate these
juxtapositions properly. By then it is
frequently too late, except at considerable
expense, to add what is discovered to be
missing or to put right what is found to be
wrong; furthermore, it is not until this
stage that it can be realized that certain
shots which are satisfactory in themselves
are nevertheless redundant.

Nor is it surprising that this state of
affairs should be so ; because of the na-
ture of the medium in which he is work-
ing, the director is in the position of an
artist denied the facility of sketching-in
the general outline of his picture and
therefore forced to bring the various de-
tails to perfection as he proceeds. It
should be recognized that the only out-
line to which the director can refer is his
shooting script. This can, however, prove
a false and misleading guide, inasmuch as
the whole art of film-making consists of
the translation of a literary form into a
visual one, and it is only visually that the
finished result can be judged.

(2) The Technique of the Electronic
Camera

The use of the electronic camera — or
rather a unit of three or four such
cameras — will obviate many if not all
of the difficulties which confront the film
director who is employing single optical
equipment. It is of the essence of the
electronic method employing more than
one camera that, during both rehearsal
and shooting, the director can view upon
his monitor screen not merely isolated
shots but complete sequences (i.e. the
blended output of his several cameras) of
whatever length he may desire. The
director can thus study the "architec-
ture" of the film whilst the construction
of the whole is still being composed, and

the element of artistic hazard intrinsic in
multiple-camera working with purely
optical cameras is entirely avoided.

The film industry has already shown
its awareness of the contribution which
the electronic camera can make to
smooth-running studio production by the
introduction of an electronic aid in the
form of a view-finder used in conjunction
with multiple optical cameras. The ad-
vantages possessed by the combination of
optical camera and electronic view-
finder may be roughly summarized as
follows. First, the element of opera-
tional blindness is removed ; the director
can study a camera-view of the shot dur-
ing both rehearsal and the actual shoot-
ing. He can satisfy himself that the
decoupage, i.e. the breakdown into shots
and angles, is as effective visually as it
appears to be on paper. He can, whilst
there is still time to alter or modify his
own intentions, watch continuous se-
quences, and he is no longer compelled
to work in a series of discontinuous
glimpses. Finally, the electronic image
can be multiplied and distributed, so that
other key workers — the producer, the
lighting engineer, the make-up super-
visor, etc. — can exercise their own sepa-
rate supervisions.

Because of these advantages the addi-
tion of the electronic view-finder to an
orthodox camera is regarded as a pro-
gressive step; nevertheless, it is essen-
tially a traditionalist solution to a prob-
lem which is amenable to more satisfac-
tory solution by newer methods. If the
electronic image produced by the view-
finder on the camera (or rather the
master image produced by the several
view-finders on the various cameras in the
unit) already exists in convenient form,
the most rewarding course would be
to improve the quality of that image until
it attains technical parity with normal
film, and then to photograph the master
image itself rather than turn back to the
individual cameras for the actual process
of recording.

Collins and Macnamara: Electronic Camera

447

The advantages inherent in this
method will already be apparent to any
director who is familiar with modern tele-
vision-studio technique. Once the elec-
tronic camera has been substituted for
the optical camera within the studio the
electronic image on the director's master-
screen becomes not merely an accurate
and helpful camera-eye view of the scene,
but an identical reproduction, faithful in
all respects with regard to lighting, focus,
tonal gradation, brilliance, etc., of the
picture which is to be, or is being, re-
corded. Moreover, the photography has
taken place at the point where the contri-
bution of the electronic unit and of the
director's supervising intelligence are at
their optimum. Not only can the
"cuts," "fades," and "wipes" be re-
corded precisely as the director wishes,
but this facility extends automatically
also to mixes and superimpositions.
Thus, at the end of shooting it is a por-
tion of the fully finished film, rather than
a collection of shots needing processing
and editing, which the director of an
electronic camera-unit has in his pos-
session.

It is not the purpose of the paper to
consider the advantages, in terms both of
financial economy and of improvement in
acting standards, which sequence shoot-
ing provides in comparison with the sepa-
rate-shot method. The main issue is the
question of the technical quality of re-
cordings made from an electronic image.
It remains, therefore, to show the reason-
ing which leads to the belief that record-
ings made by this method can produce
film of fully acceptable technical quality.

(3) Overall Technical Considerations

It is clear that, to be acceptable, mo-
tion pictures made by the process de-
scribed in the paper must to all practical
intents and purposes be indistinguishable
from those made by ordinary optical
methods. This being so, an assessment
of the average technical quality of pic-
tures intended for theatrical release must
be made, in order to determine the stand-

r~ard of technical performance which has
to be achieved to attain the requisite
effect. This is a difficult process, com-
plicated by the profound influence of the
artistic and entertainment value of the
product, but whilst recognizing the over-
whelming importance of these qualities
in their proper sphere, the engineer must
endeavour to disregard them and evalu-
ate such purely technical quantities as he
can. Even when he can assign objective
values to the more measurable qualities,
his task is still formidable, because the
final result will be judged subjectively
and no two people will agree what consti-
tutes the most acceptable product when
it comes to the portrayal of some par-
ticular scene. The most important qual-
ities which must be assessed are, in
order of relative importance, tonal range
and fidelity of tonal reproduction, and
picture definition.

( 3. 7) Contrast Range: Dealing first with
tonal fidelity and excluding specialized
shots where unusually small or distorted
contrast ranges are used for special
effects, it is generally conceded that the
average motion-picture-film print has a
useful detail-bearing contrast range of
0.2-1 .5, expressed in terms of density =
log l/#, where x is the transmission
coefficient.

Extreme highlights, such as reflections
from chromium-plated parts of motor
cars, musical instruments, sequins and to
a lesser extent glints in eyes, shine on
hair, etc., are permitted to extend to a
value of about 0.1, which is the density
of the celluloid base and constitutes a
burnt-out highlight which contains no
detail, but the presence of which is essen-
tial to give sparkle to the picture. At
the other end of the scale, there is usually
no great advantage in reproducing dark
areas of density greater than 1.5 with any
detail, because the ambient light falling
on the screen is sufficient to flatten them
out, owing to requirements of safety
lighting in theatres. Nevertheless, it is
customary to permit extremely dark areas

448

December 1952 Journal of the SMPTE Vol. 59

to reach a density substantially below 1.5
without, however, containing much de-
tail.

It may thus be said that the detail-
bearing contrast range in an average
motion-picture film, expressed in linear
terms, is antilog (1.5-0.2) = 20:1.
Allowing for extension to burnt-out high-
lights at one end of the scale (density =
0.1) and extreme blacks at the other
(density = 1.7), the total contrast range
is probably some 40:1 in the print itself.

It does not follow that this range of
contrast will always be realized on the
screen when the film is projected, because
the actual limits of reproduction will vary
enormously with many factors. The
quality of the illuminant and optical sys-
tem of the projector, the amount of am-
bient light reflected on to the screen by
different decorative schemes in the audi-
torium and many other things all contri-
bute to reduce the effective contrast of
the picture.

These considerations aside, however, it
seems clear that, to be comparable with
normal motion-picture film, the release
prints of motion pictures made by the
proposed electronic process must have a
total maximum contrast-range of some
40 or 50:1.

For the contrast characteristic re-
quired, normal practice in motion pic-
tures is to work to an overall gamma of
about 1.3, which corresponds to a mean
gamma of about unity. It is clearly
desirable that films made by the elec-
tronic method should conform to this
convention and there is no difficulty in
achieving this result. In fact, the elec-
tronic process offers the possibility of im-
provement, because the extreme flexi-
bility of the electronic chain through
which the signals corresponding to pic-
ture are passed allows almost any shape
of transfer characteristic to be contrived,
within broad limits determined by the
signal/noise ratio.

This is very significant, because it
means that inherent defects in photo-
graphs, which are cumulative through-

out the printing and processing and
which result in a far from ideal character-
istic in the final product, can be cor-
rected by electronic compensation when
the electronic camera is used, whereas
they have to be tolerated when only the
ordinary optical camera is available.
As a result, the film produced by elec-
tronic means should ultimately be su-
perior in tonal quality to that made by
normal optical methods.

(3.2} Definition: The study of definition
in a photographic image is a difficult sub-
ject, and too much adherence to conven-
tional approaches can lead to erroneous
conclusion. A somewhat novel ap-
proach to the problem has therefore been
evolved, in the hope that methods of
measurement may emerge which are cap-
able of yielding more realistic results
than some of the methods used in the
past.

For example, the resolving power of a
lens or a film stock, or a combination of
the two, is usually defined as a limiting
resolution of so many lines per millimeter.
This means that an image composed of a
pattern of that line density is just discern-
ible, i.e. it is an extinction value. Any
detail finer than this is lost, falling within
the circle of confusion of the lens or the
film grain size, or some combination of
the two.

This definition by itself is misleading in
assessing the effective sharpness of the
resultant picture. The limiting reso-
lution figure is analogous to the ultimate
cut-off" frequency of a low-pass filter, or,
with certain minor reservations, of any
piece of television equipment, such as a
video-frequency amplifier or television
broadcast transmitter. It gives no indi-
cation of the performance of the equip-
ment at frequencies in the pass region
below cut-off.

Obviously, many factors, such as lens
aberrations, flare, internal reflections and
diffusion of light and grain structure in
the photographic emulsion, etc., must
contribute to this fall-off in response as

Collins and Macnamara: Electronic Camera

449

RESOLUTION, ARBITRARY UNITS

EXTINCTION
POINT

Fig.

1. Comparison of photographic contrast with television
depth of modulation over total range of resolution.

Photography; resolution in terms of lines /mm.

Television; resolution in terms of detail frequency.

the detail fineness approaches the limit-
ing resolution or extinction value, but a
mere statement of the resolving power
does not disclose the rate at which the
fall-off takes place.

In an attempt to reconcile the tele-
vision and optical points of view, the au-
thors propose to use a term which has
come to be used, namely "detail fre-
quency," which is the product of the
number of lines per millimeter into which
the object is dissected and the scanning
speed. Detail frequency in television is
thus the electrical counterpart of detail
fineness in photography and its use per-
mits comparisons to be made. It must
be recalled, however, that 1 line/mm in
photographic practice conventionally
represents one white and one black line,
whereas in television the black and white
lines are counted separately, i.e. one
photographic line equals two television
lines. It must be added, moreover, that
the detail frequency is to be regarded as
the fundamental frequency generated by
scanning a repetitive pattern. No ac-
count is taken of harmonic development
at this stage.

Figure 1 shows an arbitrary compari-
son between the detail-frequency re-

sponse of a television system and the
detail response of a lens and photographic
emulsion in comparable terms. To
illustrate the point, the lens and film com-
bination have been shown as having
something approaching a normal aper-
ture/distortion curve, whereas the tele-
vision-system response has been main-
tained at 100% almost up to a sharp cut-
off. The limiting resolution is the same
in both cases.

It is believed that of the two reproduc-
ing systems, television will present a pic-
ture giving a greater subjective impres-
sion of sharpness and boldness of detail
than the other, even though the detail
cut-off frequencies are the same in both
cases. The theory is advanced that sub-
jective impression of definition can in
some way be related to the ratio of the
respective areas below the curves. The
determination of this effect is compli-
cated — like all comparisons of defi-
nition between television and photog-
raphy — by the fact that television pic-
tures are discontinuous in the vertical
plane, whereas photographs are continu-
ous in both planes. However, this does
not necessarily invalidate the truth of the
conception.

450

December 1952 Journal of the SMPTE Vol. 59

Illllll

' A

( t

/ \

/ I
/ \

/ \
/ \

\ /

/ \

__ I DEAL
RESPONSE

^ ACTUAL
RESPONSE

TRAVERSAL OF M I CRODENS I TOME TER

Fig. 2. Detail resolution test: (a) test card; (b) photographic image.

Another way of considering the same
effect is to study the rate of change from
black to white (and vice versa) attainable
in photography. It is known that the
transition from black to white in a photo-
graphic image is not infinitely rapid. In
other words, the density change at the
edge of an exposed area is gradual and
not abrupt. Discounting contributions
due to lack of sharpness in the lens, the
main cause of the effect is hallation or dis-
persion in the grain of the emulsion.
To demonstrate this effect, an image of
alternate black and white bars of pro-
gressively smaller dimensions is explored
by means of a microdensitometer, which
is capable of measuring the density of
areas small by comparison with the width
of the narrowest bar.

The results of such an exploration are
shown (greatly exaggerated) in Fig. 2.
The full curve illustrates the ideal re-
sponse, and the dotted curve the general
shape of results attained in practice. It
becomes apparent that the effect is pre-
cisely analogous with the distortion of a
square wave which has been passed
through an amplifier with an insuffi-
ciently short rise-time.

Investigation shows that the "rise-
time" of different photographic emul-

sions varies greatly, for example, with
grain size, etc., and it is not necessarily
those emulsions that are capable of the
greatest absolute resolution that possess
the shortest rise-time for a black-and-
white pattern of given fineness. It is be-
lieved that the picture which gives the
best subjective impression of sharpness is
the one that possesses maximum depth of
modulation at higher frequencies and
most rapid rise time, and that a figure of
merit of apparent sharpness can be ex-
tracted, based on a mathematical combi-
nation of these two values. It will there-
fore be seen that to evaluate the quality
of average motion-picture definition and
to translate the result into terms of equal
television definition is not a simple proc-
ess. In consequence, it has been neces-
sary to base the calculations on a simple
conversion using such values as are gener-
ally accepted.

Before proceeding to numerical values
it seems desirable to recognize that
motion-picture technicians have, over a
long period, arrived empirically at an
order of definition which is adequate to
satisfy the most discerning member of the
public, even when sometimes projected
through rather mediocre equipment.
There is little doubt that twice or even

Collins and Macnamara: Electronic Camera

451

four times the definition could be real-
ized, but it would be quite unnecessary
and uneconomic to do so. The generally
accepted standard seems to comprise a
lens and negative-stock combination hav-
ing a limiting resolution under best con-
ditions of about 40 lines/mm on the axis,
and some 30 lines/mm over the whole
field of a frame (22.05mm X 16.03 mm).

After processing, the release print has a
limiting resolution of about 25-30
lines/mm on the axis. This is not a very
high standard of definition, and a single-
35mm frame projected statically to nor-
mal screen dimensions generally appears
fairly soft. Under running conditions,
however, "dynamic resolution" makes its
effect apparent and helps to produce an
impression of adequate sharpness.

The mechanism of the dynamic-reso-
lution effect lies in the fact that surface
noise is random and adds from frame to
frame in quadrature. The image, on the
other hand, is repetitive and therefore
tends to add arithmetically over a num-
ber of frames; moreover, the sharpness of
edges is improved because a random suc-
cession of film grains, as it were, scan
them and sharply delineate them.

For the choice of standards of elec-
tronic-image definition to give results
comparable with motion-picture film
produced by normal methods, it is neces-
sary to consider the order of resolution
required and that realizable in the pres-
ent state of electronics. So far as image
dissection is concerned, the only variable
quantity is the number of lines, since the
picture repetition frequency is fixed by
motion-picture standards at 24 frames/
sec. The decision regarding the number
of lines controls many factors, of which
the bandwidth of the system, the signal/
noise ratio and the size of the scanning
spot at both camera and reproducing
tube are of cardinal importance. It is
well known that, for a given number of
lines, there is a calculable bandwidth
which must be used in order to produce
definition which is equal in both vertical
and horizontal directions. It is worth

remembering that the use of many more
lines than the available bandwidth justi-
fies can result only in progressive de-
terioration of the picture detail, since the
detail frequency increases as the square of
the number of lines.

The effect of increasing the number of
lines, however, has a meretricious appeal,
because of the finer resultant structure of
the picture, but, whilst easier on the eye,
it has no advantage for photography,
where the linear structure is going to be
eliminated in any case by one of the
known expedients and out-and-out detail
resolution is all that counts.

Considering, in the absence of any-
thing better, a direct translation from
optically produced film-definition stand-
ard to television, the following assembly
of facts is arrived at :

The resolution of a normal motion-
picture negative has been assessed, at
best, to be about 40 lines/mm, which
represents 80 television-picture points per
millimeter.

Since the frame is 22.05mm wide, the
definition along the line is equivalent to
a total of 80 X 22.05 = 1,764 picture
points.

This, however, is based on photo-
graphic limiting-resolution values, so
that it seems possible, in the light of the
foregoing arguments, that appreciably
less television picture points would suffice
to produce a picture of acceptable sharp-
ness. In this connection, Kemp* has
suggested that it would be permissible to
introduce a factor C, of which he con-
siders the value to be about 0.75, to com-
pensate for the more rapid decay of re-
sponse of the photographic system with
increasing fineness of detail, as opposed
to the maintenance of a high level of tele-
vision modulation up to the frequency of
cut-off. Application of this factor gives
the definition along the lines as the equiv-
alent of 1,764 X 0.75 = 1,323 picture

*W. D. Kemp, "Television recording,"
J. Inst. Elec. Engrs., [London], 99, Part III
A, No. 17: 115-127, 1952.

452

December 1952 Journal of the SMPTE Vol. 59

points. Direct translation of this value
into the number of lines from top to bot-
tom of the picture gives 1,323 X 0.75 =
992 lines. The bandwidth required to
transmit this detail, given by the familiar
l?RP/2 formula, is therefore (9922 X
4 X 24)/(3 X 2) = 15.75 me.

It will be argued that it would not give
a balanced picture, i.e. one in which
vertical and horizontal definitions are
equal, because of the line scanning factor
K. Various values have been assigned
to K, but taking it at 0.75, the number of
lines is increased to 992/0.75 = 1,320.

To sum up, therefore, definition along
the line corresponding to one-thousandth
of the picture height is required, but
to take account of diversity in the dis-
continuous vertical direction, the num-
ber of scanning lines may have to be
increased to 1,300 with a 25% increase
in bandwidth to cater for the increased
scanning speed.

However, because of the probably
greater incidence of vertical than hori-
zontal lines in a natural scene, it may
not prove necessary to go much above
1,000 lines, and, since there is a tre-
mendous advantage in keeping the
writing speed as low as possible, this
figure has been taken as a basis for first
experiments.

It must be emphasized that the whole
of the foregoing is advanced with extreme
reserve and is, moreover, the subject of
experiments currently being made, as
much of it is based on pure supposition
and on theories which have always been
the subject of fierce controversy. Doubt-
less, calculations on other bases would
yield widely divergent results, but the
authors feel that it is essential to make
some attempt to determine numerical
values, as a starting point for practical
investigation.

Quite apart from the foregoing, there
remains the possibility of introducing
novel means of picture dissection —
which may prove more adaptable than
scanning of the orthodox variety — to
the production of motion-picture film

by television methods. It is too early,
however, to make more than a passing
reference to such possibilities, and for
the purpose of the paper the authors
have confined their consideration to
scanning of the conventional type.

(4) Interlaced and Sequential Scanning

For the purpose in hand the choice
between interlaced and sequential scan-
ning involves several important con-
siderations. Interlaced scanning is uni-
versally used for broadcast television
and, in this connection, is an extremely
useful expedient. By interlacing, the
apparent flicker frequency of the re-
produced picture is doubled, without,
however, any increase in the bandwidth
required to transmit it. The principle
of interlacing therefore possesses out-
standing advantages for broadcasting
in that its use transforms a television
picture of comparatively low repetition
frequency, which would exhibit con-
siderable flicker if sequentially scanned,
into one which within acceptable limits
of brightness is effectively flicker free.

On the other hand, the introduction
of interlacing is generally held to reduce
the apparent definition of the picture as
viewed by the eye. A number of effects
are involved, of which three may be
cited. First, slight inaccuracies of regis-
tration of the interlace raster result in
"pairing" of the scanning lines, or, in
extreme cases, superimposition of the
lace and interlace lines. This is bound
to reduce the definition progressively as
the pairing effect becomes worse, until
complete superimposition occurs, when
the definition is theoretically halved.
It is only fair to record that advances in
design of scanning circuits have greatly
reduced this defect in the last year or so.

Secondly, the movement of the
viewer's eye when following vertically
moving objects strobes the line structure
and momentarily breaks the picture as
seen into half the number of lines,
giving the impression of a coarse line-
structure. A similar effect occurs in

Collins and Macnamara: Electronic Camera

453

the television camera, where strobing
can take place between the line scanning
and objects moving up or down the
vertical axis of the picture. Tilting of
the camera can produce the same effect.
It must be noted that in the recording of
a television picture strobing effects are
confined to the electronic pick-up camera
and do not occur at the photographing
point, because the photographic camera
has a fixed viewpoint. Nevertheless,
even in its reduced form, the result of
"line crawl" introduced by the camera
can be quite serious.

Thirdly, the use of interlacing gives
rise to a particularly objectionable form
of movement blur, because two discrete
and separate images of a fast-moving
object appear on the screen, displaced
from one another by the distance through
which the object has moved in the
^g-sec interval between the writing of
the two superimposed rasters. This is
a form of movement blur which finds
no counterpart in the natural response
of the eye or in normal cinematography.

On the question of recording tele-
vision images on film, however, it will
be immediately apparent that the need
for interlacing fundamentally does not
exist, because the standard picture
repetition rate is 24 frames/sec, elimina-
tion of flicker being effected at the film
projector, where the light is obdurated
twice, or preferably three times, during
the projection of each picture frame.

Freedom to use sequential scanning
leads to a consideration of its advantages,
which may be stated as follows :

(a) It is appreciably easier to obtain
accurate registration of the lines in a
sequential than in an interlaced raster.

(b) Movement blur, due to the forma-
tion of double images, and line crawl
are eliminated.

(c) The obligation to produce an
exact number of lines per frame no longer
exists, which opens up possibilities of
the introduction of advantageous effects
analogous to the dynamic-definition
effect.

(d) The number of frame-suppression
periods per picture is reduced from two
to one, thus materially increasing the
"time efficiency" of the system.

It is thus suggested that sequential
scanning presents so many advantages
that its use is to be preferred. The
serious disadvantage lies in the fact
that the pictures viewed by eye, during
production, suffer from the severe dis-
advantage of 24-cycle/sec flicker. There
seems some hope, however, that the
effect of flicker may be to a large extent
reduced by the use of reproducing
cathode-ray-tube screens having long
decay times.

(5) The Electronic Camera

(5.7) Brief Description of System: To
summarize the foregoing, it would
appear that the use of a 1,000- to 1,300-
line sequentially-scanned electronic
image with a bandwidth of 1 5 to 20 me
will suffice to give adequate definition
for the production of acceptable motion-
picture film, provided that the whole
system is sufficiently free from loss and
distortion. The contention is advanced
that definition of this order is within
range of modern electronic equipment
and that, within a short time, equipment
which has been developed in the labora-
tory will be available in a form which will
be suitable for use on the studio floor.

(5.2) Optical Performance: No limita-
tion in definition is imposed on the
system by the taking lens of the electronic
camera, since good-quality 35mm lenses
of to-day are capable at full aperture
of resolving from 8 to 10 times the
fineness of detail normally required for
making a film optically. The use of a
standard range of 35mm lenses also
ensures that depth of focus, taking angles
and so on, are exactly similar to those
to which film technicians are accustomed.

Handling Characteristics: Elec-
tronic cameras can be made in conven-
tional shape, but much smaller and

454

December 1952 Journal of the SMPTE Vol. 59

lighter than their optical counterparts.
No form of "blimp" is necessary,
because the electronic camera is com-
pletely silent. No necessity for re-
loading exists, and the cameras will
operate for long periods without atten-
tion.

Apart from this, the camera handles
in exactly the same way as any film
camera, and the camera operator, if he
so wishes, may adopt entirely con-
ventional methods of view-finding, focus-
pulling, etc. On the other hand, he has
open to him entirely new features, such
as cathode-ray view-finder, remote tur-
ret and iris operation, as well as facilities
for remote or even automatic focusing,
including splitting focus.

Only time can show how he will
choose to employ these facilities, but
it seems very probable that a technique
can be built up using some or all of
them with a material increase in effi-
ciency of working.

(5.4) Technical Performance Requirements:
The electronic camera must be capable
of resolving some 1,000-1,300 lines and
generating a substantial amplitude of
signal up to the highest detail frequency.

The photometric response must be
such that a substantially linear charac-
teristic can be obtained, with correction,
if necessary, for a 50:1 range of light
intensity.

The signal/noise ratio of the whole sys-
tem must be not worse than — 30 db on
peak white.

The camera must be free from shading
and vignetting effects and spurious sig-
nals generally, and it must maintain
constant illumination over the field and a
constant black level under the exacting
conditions of practice.

The sensitivity of the whole system
must be at least equal to or greater than
that of a normal film camera used with
fast negative stock, and the scanning
geometry must be of a very high order of
accuracy, say within 1% in terms of
velocity.

The associated equipment must have
sufficient gain for the purpose in hand
and a handling capacity large enough to
allow for pre-emphasis at the higher fre-
quencies, if necessary. It must be free
from phase distortion or overshoot
generally.

Facilities must be provided for gain
adjustment, shaping of amplitude char-
acteristic and the introduction of pre-
emphasis.

Finally, means must be provided for
cutting, fading, mixing or superimposing
the pictures from a number of cameras
and introducing electronic wipes, over-
lays, matte and other process shots, as
well as programme material derived by
telecine scanning of film taken elsewhere
of exteriors, etc.

(6) Recording Cathode-Ray-Tube Unit

As in the camera, the scanning geom-
etry of the recording unit must be of
unimpeachable accuracy and the spot
size sufficiently small to resolve the re-
quisite definition without appreciable
loss.

The tonal response must be either
linear or capable of being shaped to com-
pensate for the film-gradation character-
istics. The maximum available peak
brightness must be sufficient to repro-
duce the highest burnt-out highlight with-
out "white flattening" or defocusing.

Steps must be taken to reduce disper-
sions or reflections of light so as to pre-
serve the maximum contrast range, and
the recording tube must be set up vis-a-
vis the motion-picture recording camera
in such a way as to minimize the effects
of vibration.

(£.7) The Mechanism of Photographic
Recording: The choice of a means of
photographing the image on film in the
form of a motion picture poses a number
of serious questions. Numerous methods
have been proposed to bring about the
desired result, but, broadly speaking,
practicable methods tend to fall into one
of two main categories, namely inter-

Collins and Macnamara: Electronic Camera

455

mittent or continuous motion. The rela-
tive merits of the two systems, in their
various applications to television record-
ing are discussed by Kemp (loc. cit.), and
there is therefore no need to enlarge upon
them here.

It must be noted, however, that
Kemp's approach to the problem is con-
ditioned by the fact that his treatment
concerns the problems of recording
broadcast television, where the worker is
presented with a composite signal in-
tended for reception on a normal tele-
vision receiver. The form of this signal
is fixed and he cannot in any way vary it.

The authors, on the other hand, are at
liberty to make any changes in signal
waveform that they see fit and conse-
quently their conclusions are influenced
by the greater degree of freedom open to
them, as well as by the fact that they are
working to much higher standards of
definition, which in turn bring special
problems.

Whilst there can be no doubt that con-
tinuous motion is exceedingly attractive
from many points of view and may prove
to be the ultimate solution, the accuracy
of registration which can be realized in
the present state of development is in-
sufficient for recording pictures of the
order of definition required. In conse-
quence, attention has been directed to
the intermittent system, which has been
proved by many years' use in the motion-
picture industry to give a very high de-
gree of accuracy of registration.

The application of the intermittent
movement to the problem of recording
high-definition electronic images has, of
course, been greatly eased by the freedom
to adapt the signal waveform to suit the
operating conditions of the photographic
camera.

To illustrate the degree of this ease-
ment, consider the case of recording
broadcast television with an intermittent
camera. If the maximum picture infor-
mation is to be recorded, the film shift
must take place completely within every
other frame-suppression interval. This

means that the film must be accelerated,
decelerated, brought to rest and regis-
tered in a period of 14 television lines,
which represents a time interval of about
1.4 millisec, or 12° rotation of the film-
camera mechanism.

Expert opinion indicates that a film
shift of this speed is on the limits of possi-
bility, and that even if improved design
enabled it to be realized, the strain on
both film perforations and mechanism
would be such as to make frequent jams
and stoppages unavoidable and to render
maintenance extremely difficult and
costly.

No such mandatory condition exists in
the requirements of the proposed system
of high-definition recording, and it is
possible to choose a frame-suppression
interval of any length desired. Any in-
crease would, of course, be made at the
expense of the time efficiency of the sys-
tem, i.e. the ratio of the time during
which information is passing to the time
during which the system is inoperative
during suppression. Nevertheless, a use-
ful compromise may be struck in which
the gains accruing from the use of a
longer frame-suppression period out-
weight the loss in terms of time efficiency.

As stated earlier, the use of sequential
scanning gives a substantial gain over
interlaced scanning, since there is only
one frame-suppression period per frame
in the former as against two in the latter.
The authors, therefore, advocate an
intermittent camera with an accelerated
film-shift operating during the frame-
suppression period.

(6.2) Exposure Time and Movement Blur:
Some consideration must be given to ex-
posure time in an electronic, as opposed
to a photographic, camera. In normal
motion-picture work, the maximum
available exposure is usually 180°, and
although practice varies, the usual run of
pictures is shot at full exposure. Shorter
exposures, obtained by reducing the
shutter-opening angle, are generally used
only for scientific investigations.

456

December 1952 Journal of the SMPTE Vol.59

The effect of using a comparatively
long exposure of, say, ^g~sec in a photo-
graphic motion-picture camera is to pro-
duce a measure of movement blur, which
is usually regarded as beneficial in
smoothing out movement and preventing
the formation of discrete separate images
of a fast-moving object in successive
frames. Picture-goers are used to this
effect, and it enhances the impression of
movement as portrayed on the screen.

In the high-definition electronic
camera, the actual time the scanning
beam is traversing each picture point is
about -£% microsec, or a million-times
shorter exposure, since this would be the
effective exposure if the camera had no
memory effect. Fortunately all elec-
tronic cameras have some "memory,"
and it is possible to proportion the mem-
ory to give an adequate impression of
movement.

In the early days of television broad-
casting some cameras had a very short
memory, and a fast-travelling ball, for
instance, appeared as a line of white dots.
An exceptionally long memory, on the
other hand, is equally disadvantageous,
because under these conditions very
serious blurring will occur on moving
objects and when the camera is panned.

A compromise is therefore necessary,
and motion-picture experience indicates
that a storage memory of 0.25-0.5 frame
in length is likely to be satisfactory. It
is not thought that the effect is particu-
larly critical, and most television cameras
in use to-day do not show any unpleasant
effects in this connection under any rea-
sonable conditions of working.

(7) Choice of Film Stock

A considerable degree of latitude exists
in the choice of film stock for the record-
ing camera, by virtue of the fact that the
amount of light emitted by the recording
cathode-ray tube is independent of studio
illumination and may be kept constant
under all conditions. Processing to con-

stant gamma as opposed to constant
density is facilitated by this.

Moreover, much more light is avail-
able at the film than when it is exposed
in an optical camera, not only because
the intensity of light emitted by the
cathode-ray tube may be made several
times that of the light reflected from a
studio scene, but also because the optical
system used with the photographic re-
cording camera can be made more effi-
cient than that which it is possible to use
on a studio floor. Magnification is con-
stant and negligible depth of focus is
required, because the cathode-ray screen
is a flat field.

In consequence, comparatively slow
film stocks can be used, with advantage
in terms of resolution, rise time, absence
of granularity and linearity of tonal char-
acteristic. Moreover, images on fine-
grain negative are known to suffer pro-
portionately less in processing and print-
ing than those on more sensitive and
coarser-grained emulsions.

(8) Conclusion

Whilst encouraged by the results of
laboratory and studio tests to date, the
authors are conscious that the paper is
necessarily tentative in its conclusions
and is in many respects lacking in precise
data. However, in view of the rapidly
developing interest in electronic film-
making, they felt that an interim paper of
this nature would nevertheless be of
interest.

(9) Acknowledgments

The authors are indebted to: Pye.
Ltd.; the J. Arthur Rank Organization;
London Film Productions, Ltd.; East-
man Kodak, Ltd.; E. F. Moy, Ltd.;
and W. Vinten, Ltd., for information and
assistance.

The authors also wish to express their
thanks to Mr. W. D. Kemp and Mr.
B. R. Greenhead for their help in the
preparation of the paper.

Collins and Macnamara: Electronic Camera

457

Discussion for This Reprinting
By Pierre Mertz

The paper by Messrs. Collins and
Macnamara describes a proposal that
will be followed with great interest, for
the application of television to motion
picture production techniques. The
objective "that, to be acceptable, motion
pictures made by the process described
in the paper must to all practical intents
and purposes be indistinguishable from
those made by ordinary optical methods"
will appear especially challenging.

A point which the authors un-
doubtedly have in mind, but do not
emphasize, is that in large measure the
television processing which they are
proposing is to be inserted in tandem
with the photographic and optical
techniques at present existing. Thus
to set detailed objectives on quality it
is necessary to investigate not merely
the performance of the latter processes,
but also the additional impairment
expected from the insertion of the
television processing. In such a case,
in general, the inserted impairments
need to be not simply of the same order
of magnitude as those already existing
(in the optical and photographic proc-
esses) but one or two orders of magni-
tude lower.

The authors are diffident about the
tentativeness and controversial nature
of their data and conclusions on photo-
graphic and television performance.
Because of this it would seem helpful
in a number of places if they could
give documentation for the data they
introduce. In particular, the authors
have not referred to the extensive work

At the request of the Chairman of the
Society's Board of Editors, at the time of
reviewing this paper, this discussion was
prepared by Pierre Mertz, Bell Telephone
Laboratories, Inc., 463 West St., New
York 14, N.Y.

of Otto Schade1 on many questions
which apply closely to their problem
Other specific points upon which docu-
mentation would be helpful are:

(a) The film density ranges men-
tioned by the authors seem modest
compared to the projection density
measurements reported by Tuttle2 in
1936. Tuttle's minimum densities run
a bit higher than the authors': at low,
0.18; median, 0.41; and high, 1.05.
His maximum densities, however, run
substantially higher: namely, low, 1.90;
median, 2.21; and high, 2.65. The
influence of stray light in the theater
on the projection contrast was discussed
in a symposium of the SMPTE in May
1951.3 S. K. Guth, in particular,4
mentions a maximum desirable level
giving 0.07 ft-L on the screen (which
has a clear screen brightness of 5 ft-L).
This leads to an equivalent density of
1.85, which still is over the authors'
allowance of 1.7.

(b) The authors' figures on motion
picture definition correspond generally
with those found by an SMPTE com-
mittee in 1946 and referred to by
Schlafly5 in 1951. It would be interest-
ing, however, to have more specific
information on the "good-quality 35mm
lenses of today . . . capable at full
aperture of resolving from 8 to 10 times
the fineness of detail normally required
for making a film optically."

(c) The explanation which the authors
give of "dynamic resolution" is the
conventional one. However, in any
casual experience which I have had,
the increase over the "static resolution'*
was not realized, possibly due to "jump"
and "weave" of the picture. It would
be interesting to have any documenta-
tion on actual experiments which the
authors might know of.

(d) Again on the subject of definition,

458

December 1952 Journal of the SMPTE Vol. 59

the Fig. 1 which the authors show
represents the familiar sharp drop in
television resolution towards the ex-
tinction point. However, it has been
shown in the work by Schade that if
the influence of terminal equipment is
considered in addition to that of the
electrical circuit, the shape of the charac-
teristic obtained shows a gradual drop,
not too different from the photographic
characteristic. This is illustrated, for
example, by Figs. 100 and 101 of the
1948 paper.6

(e) The authors attribute to Kemp a
suggestion for the use of a factor C =
0.75 to compensate for the decay,
towards the extinction point, of the
resolution of the photographic as com-
pared with the television system. I
have read through the Kemp paper
referred to, No. 1351, fairly carefully
but cannot find the suggestion.

(f) The authors mention a proposed
signal-to-noise ratio requirement, to
avoid degrading the film picture, of
30 db. American estimates of the
performance of film run appreciably
higher.7 Figures (excluding allowances
for synchronizing pulse and excluding
frequency weighting) have been pre-
sented of 42 to 47 db, and even higher.
Possibly the authors are measuring the
random noise peak-to-peak, instead of
rms, but even this would not account
for all the apparent discrepancy. It is
noted that no figures at all are given
on specifications for shading or phase
distortion, although these are apt to
be important impairments in present-
day television.

(g) It would be interesting to know
if the authors have any specific informa-
tion in mind on the "probably greater
incidence of vertical than horizontal
lines in a natural scene."

It is a little odd to find, after an
admirable discussion of the advantages to
be gained by the presentation to the
director of exactly the picture which
will ultimately be obtained from the
film, that the authors are so little

bothered by the problem of flicker on
the director's monitor. With the use
of the sequential scanning and the frame
frequencies mentioned, together with a
useful picture brightness, one wonders
if the flicker will not be sufficient to ruin
the director's artistic judgment. It
would be interesting to have more
information on the speculations regard-
ing the possibilities of long decay phos-
phors in avoiding this, without unduly
blurring the outlines of objects in
motion.

References

1. O. H. Schade, "Image gradation,
graininess and sharpness in television
and motion picture systems: Part
I — Image structure and transfer char-
acteristics," Jour. SMPTE, 56: 131-
177 (see p. 137), Feb. 1951.
"Part II — The grain structure of
motion picture images — an analysis
of deviations and fluctuations of the
sample number," ibid., 58: 181-222,
Mar. 1952.

"Electro-optical characteristics of tele-
vision systems: Introduction," RCA
Rev., 9: 5-13, Mar. 1948.
"Part I — Characteristics of vision and
visual systems," ibid., 13-37, Mar.
1948.

"Part II — Electro-optical specifications
for television systems," ibid., 245-286,
June 1948.

"Part III — Electro-optical charac-
teristics of camera systems," ibid., 490-
530, Sept. 1948.

"Part IV — Correlation and evaluation
of electro-optical characteristics of imag-
ing systems," ibid., 653-686, Dec. 1948.

2. C. M. Tuttle, "Density measurements of
release prints," Jour. SMPE, 26: 548-
553, May 1936.

3. "Symposium on Screen Viewing Fac-
tors," held May 2, 1951, at the Society's
Convention at New York and published
in Jour. SMPTE, 57: 185-246, Sept.
1951.

4. S. K. Guth, "Surround brightness: key
factor in viewing projected pictures,"
Jour. SMPTE, 57: 214-224, Sept. 1951.

5. H. J. Schlafly, "Some comparative
factors of picture resolution in television

Collins and Macnamara: Electronic Camera

459

and film industries," Jour. SMPTE,
56: 44-51, Jan. 1951.
6. O. H. Schade, from reference 1 above,
RCA Rev., 9: see p. 678, Dec. 1948.

7. Pierre Mertz, "Data on random noise
requirements for theater television,"
Jour. SMPTE, 57: 89-107, Aug. 1951.

Author's Comments

The authors were careful to point out
that this paper was of an essentially interim
nature, and did little beyond defining some
of the major difficulties with which those
who seek to make motion pictures by a
television intermediate process are faced.

This being the case, the authors de-
liberately refrained from making reference
to the very considerable amount of bibli-
ography which exists on this subject.

The introduction of any additional
process into a reproduction system must
degrade the result unless the additional
process can be made to correct errors in
the process. It is certainly possible to
apply electrical corrections for tone dis-
tortions introduced by the film charac-
teristics, and by overemphasis of the higher
detail frequencies it would appear also
possible to correct in a large degree for
aperture distortion, lens losses, etc. (As
an analogy it is interesting to recall that
the introduction of an electrical process
into the recording of sound on disc —
essentially a mechanical process — con-
siderably improved the overall results.)

The authors, moreover, believe that
other gains in terms of definition can be
achieved. For example, it appears that
the present average standard of quality
in motion pictures has gradually advanced,
against economic pressure, to a state
where it is generally acceptable to the
picture-going public. There seems good
reason to suppose that if higher processing
costs could be justified, marked improve-
ments could be effected both in the pro-
duction of the original negative and its
subsequent reproduction through the stages
leading up to the multiple release print.

The authors feel that if the economic
advantages they claim for the process
which they advocate are realized, some
proportion of the savings will be available
to improve the photographic part of the
process with considerable gain in overall
results.

Dealing now with the other points in

the discussion, the authors would make the
following comments:

(a) The film density ranges which
they have mentioned were those quoted:
by a well-known manufacturer of film
stock and the authors took them as a fair
average basis on which to work. In
point of fact there is no difficulty in extend-
ing the contrast range to any value which
the film will accept so that the figures
reported by Tuttle could be realized with-
out serious difficulty.

(b) The authors admit that the state-
ment that "good-quality 35mm lenses of
today are capable at full aperture of
resolving eight to ten times the fineness
of detail normally required for making
a film optically" is misleading if divorced
from its original context, which was
omitted from the paper at a late stage for
security reasons. They can only repeat
the view of a leading lens designer who
states that "an f/2 lens can provide on
Maximum Resolution Plates, 8 to 10 times
the axial resolving power obtained with
emulsions used in the film industry. Thus
one could argue that it is the fact that the
film industry uses grainy emulsions which:
defines fineness of detail."

The authors hold the view that this
increased resolving power may to some
extend be exploited.

(c) The authors believe that the con-
ventional explanation of "dynamic resolu-
tion" is valid, and although it is difficult
to establish quantitative results they have
carried out a number of experiments which
by observation were extremely convincing
and in which the effect of dynamic resolu-
tion was most marked.

(d) The authors are only too well aware
of the losses introduced by terminal equip-
ment and as previously stated have been
at pains to introduce into the electrical
circuits corrections to compensate as far
as possible for them. The limit to this
process is, of course, the signal-to-noise
ratio. To date they have been surprised

460

December 1952 Journal of the SMPTE Vol. 59

at the good signal-to-noise ratio they have
been able to obtain.

By scrupulous attention to every element
in the chain they have been able to preserve
a good relationship between contrast in
the object and in the image photographed
on film up to the highest resolution powers
of which the system is capable. They are
confident that this result is capable of
extension to higher definition by expedients
which they hope to describe in due course.
It should be mentioned in passing that
particular attention has been given to the
design of kinescope recording tube screens
so as to maintain high contrast at the
finest detail and eliminate as far as possible
reflections and diffusion effects which
militate against the desired result.

(e) The factor attributed to Kemp was
omitted from the published version of his
paper.

(f) The acceptable ratio between signal
and noise seems to depend largely on the
nature of the noise. The authors took a
number of examples of optically produced
film exhibiting normal grain structure and
made a series of statistical tests against
television picture recordings on fine-grain
film in which the noise was of a fairly
high-frequency type.

When the two results were adjudged to
be as nearly comparable as could be
determined by observation, the level of
peak noise in the television picture was
found to be some 30 db below peak white.

Had there been a preponderancy of low-
frequency noise in the television picture
it is highly probable that some ratio of
the 40-50 db order would have been
required, because not only is the high-
frequency noise attenuated in the photo-
graphic process, but it is less apparent to

the eye because of its finer structure.

As regards shading and phase distortion,
the authors have worked to a condition
of no visible shading in the photographic
image, but with a progressive increase in
brightness towards the edges of the picture
amounting to some 15% at the extremes
to compensate for lens vignetting. It has
been found advantageous in some cases
to overcorrect the final product to com-
pensate for the projector objective. Phase
compensation throughout the system is
advocated so that no visible overshoot
occurs at any frequency within the limits
of the response of the system.

(g) The authors regret that they cannot
quote any scientific evidence regarding the
greater incidence of vertical as opposed to
horizontal edges in a natural scene, but
they have frequently heard the view
expressed that the former tend to pre-
ponderate.

In conclusion, the question of nicker on
the director's viewing screen has proved
curiously unimportant. At a brightness
consistent with fairly low levels of ambient
illumination the flicker is singularly
inobvious and after a few minutes the
observer gets used to it and forgets it
entirely. The wearing of dark glasses
has been recommended and certainly
assists in this connection, but never at
any time during the authors' work has
any serious complaint of flicker been
voiced. Reproducing tubes having a
moderate decay are used at present and
the development of tubes having some
approximation to a square decay has made
some advance. Unfortunately, however,
no information can be disclosed on such
tubes at the present time for security
reasons.

Collins and Macnamara: Electronic Camera

461

Signal Corps

Mobile Television System

By JOHN S. AULD

The U.S. Army Signal Corps* mobile television system is briefly described.
In this system five vehicles — a transmitter bus, transmitter power bus, re-
ceiver bus, receiver power bus, and kinescope recording bus — are used to
provide a complete television unit designed to meet training and operational
requirements of the Army.

N 1948, when television began to
pass from its embryonic stage, the Army
decided that it might be employed to
answer some of its tactical and training
problems. Television had been used
during the latter phase of World War II
on an experimental basis, using highly
specialized nonstandard equipment, with
excellent results.

The question arose as to what units
would receive television equipment,
what type, and how would it be em-
ployed? It was decided that the most
practical and economical method of
answering these questions was to design
one complete and self-contained system
on wheels. This unit could then travel
from post to post stimulating thought,
and showing field commanders of the

Presented on October 7, 1952 at the So-
ciety's Convention at Washington, D.C.,
by Sgt. John S. Auld, Technical Director,
U.S. Army Signal Corps Mobile Tele-
vision System, Signal Corps Photographic
Center, 35-11 35 Ave., Long Island City 1,
N.Y.

various branches of service (i.e. artillery
infantry, etc.) how television might solve
some of their particular problems. The
information obtained from these demon-
strations would then form the basis for
specifications of specialized equipment
to meet these individual needs. This was
the inception of the Signal Corps Mobile
Television System.

The Transmitter Bus

The basic layout of this vehicle is quite
similar to that of the average commercial
remote pickup bus but, because it has
to provide all the station programming
facilities, it is much more elaborately
equipped.

This unit houses three, RCA Type
TK-30A, field camera chains. The
camera controls and power supplies
are placed console fashion across the
rear of the bus. Behind this operating
position there are five cable reels. Four
of these carry 250 ft of camera cable
each; the fifth, 1700 ft of microphone
cable of various convenient lengths.

462

December 1952 Journal of the SMPTE Vol. 59

John S. Auld: Mobile Television System

463

COAX FEED TO
KIN* RECORDING BUS

Fig. 2. Transmitter bus — video distribution.

It may be stated here that all the reels
in the vans are power-driven on take-up
by an ordinary portable electric drill
with a J-in. chuck. Needless to say
that since the system carries 18,000 ft
of assorted cable this is quite a time and
labor saver.

Originally the film chain was placed
in the receiver bus due to a lack of space
in the transmitter bus. This handi-
capped the program director in that he
could not preview film. When a kine-
recording unit was added it was decided
to remove the film chain from the re-
ceiver bus and place it in the kine-
recording van since this van was to be
located next to the transmitter bus and
the two attached directly by cable.

Film video signal now feeds through

coaxial cable to an isolation amplifier
in the transmitter bus and from there to
an auxiliary input of the switcher where
it can be previewed on the master moni-
tor by throwing a monitor selector
switch.

As can be seen in the block diagram
of Fig. 2, the line output of the switcher
feeds both the microwave unit (a stand-
ard RCA Type TTR-1B on 7125 me)
and the kine-recording bus through a
paralleled distribution amplifier. The
auxiliary output is also paralleled to
feed the TM-2A auxiliary monitor in
the cab, an announce position, and also
a feed for stage monitor.

Two RCA Type OP7 portable mixers
feeding a single OP6 amplifier provide
eight low-level audio inputs. For ac-

464

December 1952 Journal of the SMPTE Vol. 59

1 1

MICR

| |

TURNTABLE

OP 7

AND

MIXER

RECORDER

AMPLIFIER

CROPHONE INPUTS

I I I

Fig. 3. Transmitter bus — audio distribution.

cessibility and ease of operation all
microphone inputs, P.A. speaker feeds
and intercommunication jacks are
mounted on an aluminum strip which
runs the width of the bus just below the
cable reels. An RCA RT-11A rack-
mounted (studio-type) tape recorder, a
portable disc recorder-turntable, and
a 30-w Brook amplifier with a bass
reflex speaker used as a monitor system
assure adequate audio facilities.

Figure 3 shows a simple block dia-
gram of the audio layout. The OR-1A
amplifier and its associated speaker
serve as a public address or talk-back
system when necessary.

The audio signal is transmitted to the
receiver bus by a 45-w, phase-modulated,
police transmitter which has been

modified for high fidelity. A four-
element yagi* is used as an antenna.
A bridge off the program line feeding
the transmitter feeds audio signal to the
kine-recording van.

Each of the four vans is equipped with
an FM transceiver on 163 me which
serves as an engineering line. Pro-
vision is made to operate these units
from the bus battery as well as a-c so
that communication can be maintained
while the vehicles are in motion. An
additional transceiver, on 173 me, is
provided in both the transmitter and

* Antenna array devised by Hidetsu Yagi
in 1928. It consists of an active dipole
and several short-circuited dipoles serving
as directors and reflectors, to give a narrow
beam.

John S. Auld: Mobile Television System

465

receiver bus as a production line and
also as an emergency audio transmitter
in case of failure of the main 45-w
equipment.

The transmitter bus can operate on
either a three-phase, four-wire, 220/110-
v or a single-phase 1 1 0-v system. Three
variacs used in conjunction with a volt-
meter provide for balancing the load.

The Transmitter Power Bus

A serious difficulty in most remote
pickup setups is power availability.
The purpose of this vehicle is to remove
this problem. It houses two 15-kva
motor generators in a compartment just
aft of the cab. A single 55-gal gas
tank serves both the bus and generator
motors. This allows the generators to
run under full load for ten hours without
refueling which is more than enough
time for the average demonstration.

The generators supply three-phase
208/11 0-v power to two Russell and
Stoll output plugs located on the side
of the bus. By connecting the output
of each generator to the arm of a 3-pole,
double-throw switch either generator
can feed either plug or in emergency any
one generator both plugs. The gover-
nor on the motor holds the output
frequency within a half-cycle once it
has been adjusted for a constant load.
By operating the synchronizing gener-
ators with a long time-constant in the
AFC circuit they lock in very well on
60 cycles.

Two 250-ft reels of four- wire jf6
power cable are utilized to keep the
line losses low while separating the
vehicles to minimize the generator noise
in the audio pickup. Two other reels
carry additional camera cable, RG-11U
coaxial cable for video feeds, and two-
wire #10 cable for lighting and power
extensions. The reels are accessible
from the outside by the use of small
ports in the side of the bus.

The rear compartment of this vehicle
contains two work benches for equipment
maintenance. Below the benches and

the reels are cabinets and drawers for
spare parts and tools. The drawers
have removable dividers for greater
utilization of space.

The Receiver Bus

As its name implies this vehicle
provides the receiving facilities for the
system. This consists of ten 16-in.
receivers and one large-screen pro-
jection receiver which have been modi-
fied so that they are capable of being
either "line" or "air" fed. As was
mentioned previously, this unit may be
located up to 20 miles from the point of
program origin.

Most of the equipment used in re-
ception is contained in two 6-ft racks
mounted in the rear of the bus. Two
doors make the back of the rack easily
accessible from the outside.

Video signal from the microwave
receiver is passed through a stabilizing
amplifier to clean up the synchronizing
pulses and to make sure of the syn-
chronizing pulse-to-video signal per-
centage. This stabilizing amplifier has
two outputs, one of which feeds a 12-in.
monitor mounted alongside the rack and
the other feeds two unity-gain distribu-
tion amplifiers having ten isolated out-
puts. The input and output of all
equipment comes up on coaxial patch
panels with parallel jacks for versatility
and quick checking with an oscilloscope.
In the present setup the output from
one of the distribution amplifiers feeds
a "Dumitter." The Dumitter is a closed
circuit (nonradiating) transmitter whose
function is to take audio and composite
video signals and modulate a carrier on
television channel 3. This modulated
RF signal can then be sent over coaxial
line to as many as 125 commercial re-
ceivers of 72-ohm input using a line
distribution arrangement without modi-
fying the receiver to a line-driven
monitor. Small distribution boxes are
provided with the Dumitter having one
input and five outputs. By utilizing
these boxes all ten receivers may be

466

December 1952 Journal of the SMPTE Vol.59

placed up to 1 500 ft from the bus by the
outlay of only 3000 ft of RG1 1/U coaxial
cable, and ten small lengths of RG59/U
to couple the boxes to the receivers. To
accomplish this same feat using the stand-
ard distribution amplifiers carried in the
receiver bus would mean running 15,000
ft of special cable (single coaxial and an
audio pair). Eleven 500-ft lengths of
this special cable were supplied with the
system but along with the distribution
amplifiers are now relegated to emer-
gency and special service.

Program audio signal is received on a
single-channel FM receiver with double
conversion. A four element yagi is
used as an antenna. The receiver
output feeds the Dumitter, a monitor
amplifier, and a multi-winding trans-
former with one input and eleven
outputs. This transformer provides a
direct "line" feed to the receivers when
desirable.

Three auto-transformers boosting the
line voltage 5 v feed eleven a-c outlets
located in the rear of the bus. These
outlets are used in conjunction with
5,500 ft of two-wire #12 cable, carried
in the receiver power bus, to provide
power to the receivers. The auto-
transformers make up for the losses
incurred by long power runs.

The Receiver Power Bus

The layout of this vehicle is quite
similar to that of the transmitter power
bus. The main difference is that it
has one 15-kva motor generator which
allows for a larger rear compartment.
This compartment contains ten reels
which hold 500 ft of microwave cable,
250 ft of four-wire #6 power cable,
5,500 ft of special receiver cable, 5,500
ft of two-wire #12 receiver power cable,
2,000 ft of RG11/U coaxial cable, and
1,500 ft of RG59/U coaxial cable.
This compartment also houses two work-
benches. One of these is set up as a
receiver test bench complete with tele-
vision sweep generator, sweep calibrator,
vacuum tube voltmeter and oscillo-

graph. Cabinets and drawers, below
the workbenches and reels, house spare
tubes and parts.

The Kinescope Recording Bus

This unit is the latest addition to the
system. The vehicle is a Fagoil-type
"Twin Coach." It is a standard Army
vehicle and is ordinarily used as a 36-
passenger bus or for carrying litter
patients. Upon receiving this unit we
removed the seats, blanked out the
windows and in general, made the
operating section of the bus light-tight.
A plywood partition with a sliding door
separates the cab from the operating
section.

Ordinarily, prints are made of the
"kine-recordings" so negative recording
is used and the sound recorded on a
Westrex 16mm portable tape recorder.
When only a single print is desired
positive recording is used and the sound
recorded right on the film by a Maurer
sound head. At the time of writing no
development and printing methods have
been established since the installation
has not been completed.

As mentioned previously, the icono-
scope film chain is now located in this
vehicle. The chain has been laid out
in such a way that one man can handle
the operation without leaving his operat-
ing chair.

The bus contains cabinets for film
and spare parts storage. Two reels
contain enough cable to locate this
vehicle up to 150 ft from the transmitter
bus. The reels are accessible from the
outside of the vehicle.

Employment of the System

After a period of testing and break-in
the unit embarked on its first mission 1 8
February 1952. This mission was to
provide television facilities for the Army
Field Force Commanders' Preventive
Maintenance Course held at Aberdeen
Proving Ground, Maryland. Upon ar-
rival demonstrations were set up and a
weekly schedule arranged. Four of

John S. Auld: Mobile Television System

467

n nnni~

Mill

i i i

i r» i

RF TO RECEIVERS

Fig. 4. Receiver bus — audio-video distribution.

these shows were studio presentations
and covered preventive maintenance in
the various branches of service. The
other two were remotes of which more
shall be said later.

For the studio presentations a theater
was utilized. The transmitter bus was
used as a control room. Ample com-
mercial power was available so the
motor generators were not needed.
Camera cables, microphone cables, talk-
back and PL lines, and coaxial cable
feeds for stage monitors were run into
the rear of the building. The theater
had only been used for motion pictures
and therefore had very poor lighting
facilities. Scoops and spots were ob-
tained to supplement the portable
lighting equipment carried by the system.
Everything was installed on a semi-

permanent basis so that if a remote
pickup was contemplated the only thing
necessary was to disconnect the cables
from the van, load in the cameras and
be off.

The receiver bus was parked close
by with five video-audio lines to two
classrooms. The large screen projection
system was installed in the front of the
classroom flanked on either side by a
1 6 in. receiver for students whose viewing
angle to the large screen was too acute.

Each week the officer-students
answered a questionnaire after seeing
the foregoing productions. Results
showed that the utilization of television
as a training aid was highly successful.

The most important of the remote
pickup programs was entitled "The
Video War Room." This program

468

December 1952 Journal of the SMPTE Vol. 59

taxed the engineering facilities of the
system to the utmost. The production
portrayed tactical television as it might
function in the future. Cameras were
concealed in a barn loft observation
post, and by utilizing some eighty
enlisted men as friendly and aggressor
troops, along with tanks and planted
charges, it realistically demonstrated
how television front line cameras could
send information back to division level
where it could be analyzed by the
Division Commanding General and his
staff and acted on accordingly.

While this production fulfilled the
unit's primary mission of stimulating
thinking about the tactical use of
television, it also emphasized to the
engineer the need for simple, compact
portable equipment with a low power
drain.

In May 1952 the unit participated in
several exhibitions including the Armed
Forces Day Exhibition at Boiling Field,
Washington, D.C. The unit then de-
parted for West Point, where it provided
television facilities and was on exhibition
for June Week.

Closed-Circuit Television Demonstration at NOL

The use of short-range closed-circuit
television for scientific and plant opera-
tion demonstrations is attracting wide
attention in many areas today.

The 72nd Semiannual Convention of
the SMPTE held one meeting in the
U.S. Naval Ordnance Laboratory.
Since security restrictions and time
would not have permitted the members
to visit the large wind tunnel facilities,
a telecast was arranged through the
medium of a closed-circuit television
system provided by the Army Signal
Corps.

The audience of approximately 150
persons was addressed by Dr. H. H.
Kurzweg, Chief of the Aeroballistics
Research Division, in the NOL audi-
torium. * Then the program was switched
to the wind tunnel building about one-
half mile away. The picture and sound
for the telecast from the wind tunnel
were transmitted over an interconnecting
relay link. The picture was viewed on

Supplied by Mary T. Kanagy, Public
Information Officer, U.S. Naval Ordnance
Laboratory, White Oak, Silver Spring 19,
Md.

* For auditorium details see D. Max Beard
and A. M. Erickson, "Auditorium specifi-
cally designed for technical meetings,"
Jour. SMPTE, 59: 205-211, Sept. 1952.

theater projector system and several
standard television receivers in the
auditorium. Sound was heard through
the auditorium sound-reinforcing system
and was recorded through the plant
sound-recording system.

A communication system was set
up to interconnect the wind tunnel
program director, link transmission
truck, link receiver truck, auditorium
moderator and the recording facility.
Included in the system were extensions
to dial phones, special telephone lines
and radio transceivers where telephone
lines were not feasible.

Through television, the audience saw
and heard actual wind tunnel operations
explained by the Chief of the Design
and Operations Division, J. R. Lightfoot.
Schematic diagrams were used to demon-
strate the essential components of the
large supersonic wind tunnels for re-
search and development testing at
equivalent air speeds up to five times
the speed of sound and of the similar
hypersonic tunnel at speeds up to ten
times that of sound.

The working section of the large
Tunnel 1 was kept open to show the
nozzle contour and the missile model
positioned on its support. Tunnel 2,
also a 40 X 40 cm tunnel and identical

John S. Auld: Mobile Television System

469

470

December 1952 Journal of the SMPTE Vol. 59

in most respects to Tunnel 1, had a
similar model mounted in its working
section and was actually operated.

After the test models of missiles had
been displayed and basic instruments for
measuring pressures, forces, and tempera-
tures demonstrated, air was blown
through Tunnel 2 at supersonic speed
and a schlieren picture of the shock
waves about the missile model was
picked up on television camera 3 and
telecast to the auditorium. At the same

time the audience observed pressure-
measuring instruments in actual use
and saw much of the operation which
would have been difficult to demonstrate
to a large group of visitors even had a trip
to the tunnels been possible.

The telecast concluded with a state-
ment of planned improvements and
future modernization of the plant,
instrumentation and scientific tech-
niques.

John S. Auld: Mobile Television System

471

Motion Photography
for Combustion Research

By F. W. BOWDITCH

The history of the use of semi-high-speed photography as a research tool for
the study of the combustion process in gasoline engines at General Motors
Research Laboratories is presented. The investigations consist of direct
photography of the luminous combustion process as seen through quartz
windows in the heads of several gasoline internal combustion engines. Both
commercial cameras and cameras designed and built in these laboratories
were used.

JL HE USE OF photography to study the
combustion process as it occurs in a
gasoline internal combustion engine was
first successfully attempted1 at the
Research Laboratories Division of
General Motors Corp. in 1930. Until
then practically all information known
about gasoline engine combustion had
been obtained from pressure-time cards
and from sampling valve studies. The
results of the pressure card and sampling
valve studies indicated that these methods
alone could not completely describe the
physical aspects of the combustion
process.

It was decided that by taking photo-
graphs of the combustion process through
a quartz window mounted in the head
of a single-cylinder engine a physical
picture of the combustion process could
be obtained. Since the use of a quartz
window in the head of an engine was
entirely new, it was decided that a

Presented on October 9, 1952, at the
Society's Convention at Washington, D.C.,
by F. W. Bowditch, Research Laboratories
Division, General Motors Corp., Detroit
2, Mich.

long, narrow quartz window would be
the easiest to install and seal. Such a
window 5 in. long and 0.375 in. wide
was built into the head of a single-
cylinder engine in a manner shown in
Fig. 1. A film drum was mounted
over the engine, with the axis of the
cylinder parallel to the major axis of
the quartz window, and a Meyer
Plasmat //1. 5 lens was used to focus
the quartz window on the drum.
The drum and a focal-plane type shutter
were driven from the camshaft of the
engine in a direction normal to the
direction of flame travel in the engine.
The engine and camera equipment are
shown in Fig. 2. Eastman Portrait
Panchromatic cut film was wrapped
around the drum, sufficient circumferen-
tial drum space for the film being
provided so that enough film for one
explosion could be used at a time.
Examples of knocking and nonknock-
ing type of flame record obtained are
the upper parts of Fig. 3. Photographs
of the ignition sparks appear at A and
of timing sparks at B, 20° later. The
flame photographs were taken with the
film moving toward the left and the

472

December 1952 Journal of the SMPTE Vol. 59

WATER SPACE

Fig. 1. Views of the cylinder head, showing the location of the quartz window
and the general shape of the combustion chamber; left, plan of the ceiling of the
combustion chamber; right, longitudinal section of the cylinder head.

RLM

DRUM

FILM
DRUM
DRIVE

PRESSURE
INDICATOR

END OF
WINDOW
RETAINER

Fig. 2. The first combustion camera mounted upon the engine.
F. W. Bowditch: Research Photography

473

flame moving from the bottom to the
top of the photographs. The upper
sloping edge of the light portion was
therefore a time-distance plot of the
flame front movement across the com-
bustion chamber. The region marked
afterglow in the photographs was pro-
duced by the burned but luminous gas
behind the flame front.

It was from these researches that it
was definitely determined that normal
combustion in a gasoline engine was
initiated at a single point — the spark
discharge — and spread from this point
like a grass fire at a rate which could
be determined from the slope of the
pictures similar to the flame records of
Fig. 3. It was also found that during
the combustion process there is a rela-
tively narrow zone in which all of the
combustion process takes place and
which moves progressively through the
charge.

From this type of record it was found
that flame speed is proportional to
engine speed and that knock in a gasoline
engine consists of the last part of the
charge burning at a rate many times
that occurring under normal combustion
conditions. This is illustrated by com-
paring the flame records of Fig. 3. So
it was that the first photographs of the
burning of gasoline and air in a spark
ignition engine furnished many of the
basic facts which are now used daily in
the design of better automobile engines.

This type of photography was limited,
however, particularly in regard to de-
termining the shape, structure and move-
ments of the flame fronts and the nature
of knock. In particular it was hoped
that flame photographs would supply
information regarding the effect of
engine speed, chamber shape, fuel types,
etc., on the rate of flame travel. These
considerations led to the development of
another engine which allowed an un-
restricted view of the entire combustion
chamber. The head and cylinder block
are shown in Fig. 4. The problem of
sealing the quartz window in the head

frame required many hours of research.
The problem facing the investigators
at the time the original plans for the
engine were drawn up was what type
of camera could best be used for taking
photographs of the combustion process
through the full quartz head.
• At this time a number of high-speed
camera designs were available in the
literature; however, careful considera-
tion of the following aspects of the photo-
graphic problem showed that many of
these cameras would be unsuitable:

1. The subject to be photographed
was self-luminous; that is, the light
was emitted from the flames themselves.
This imposed a severe limitation upon
camera design from an exposure stand-
point and ruled out those cameras
which depended upon a separate high
intensity source of illumination.

2. The picture frequency had to be
relatively high since the flame front
moved at a high velocity from the spark
plug across the combustion chamber.
Under normal operating conditions at an
engine speed of 2000 rpm a frame speed
of 5000 frame/sec was required in a
combustion chamber 5 in. long to obtain
20 pictures of the combustion process.
At 400 rpm, however, a frame speed of
only 1000 frame/sec was required for
the same number of pictures of the
combustion process.

3. The available light was fixed by
the engine conditions and could not
be varied at will. Experiments with
the original flame camera showed that
satisfactory results could be obtained
with an exposure of 0.0002 sec and an
engine speed of 1200 rpm, with an //1. 5
lens using a hypersensitive panchromatic
film. Consequently, the light emitted by
the combustion process was sufficient
for frame speeds of 5000 frame/sec at
an engine speed of 2000 rpm provided
the duration of exposure was comparable
with the time interval between frames
and provided the lens speed was //1. 5
or greater throughout most of the ex-
posure. In order to fulfill these condi-

474

December 1952 Journal of the SMPTE Vol. 59

ENGINE KNOCKING

ENGINE NOT KNOCKING

Fig. 3. Pictures show the effect of knock on the flame and pressure records;
A, time of ignition; B, 20 deg after ignition.

Fig. 4. Photograph of the
head and block of the full-
view quartz window L-head
engine.

F. W. Bowditch: Research Photography

475

Fig. 5. Schematic drawing of camera.

A. Ignition breaker

B. Intake port
G. Exhaust port

D. Combustion chamber

E. Spark plug hole

F. Quartz window

G. Invar window frame
H. Stellite mirror

I. Stationary field lens

J. Lens stop

K. Shutter

L. Rotating disk

M. Moving lens

N. Prism

O. Focal plane shutter

P. Film

Q. Door in light-tight housing

R. Gam follower which actuates shutter

S. Shutter cam

T. Crankshaft

476

December 1952 Journal of the SMPTE Vol.59

dons the film and image had to be moved
together.

4. In order to obtain the minimum
amount of blurring due to the rapid
movement of the combustion process, it
was necessary to utilize the shortest
possible exposure time. Since light
intensity could not be varied at will, the
other alternative was to maintain a
maximum lens speed during the entire
exposure. This type of operation is
approximated with the use of a focal
plane shutter.

5. The picture could not be so small
as to lose the details of the combustion
process. A standard 16mm frame was
chosen as the smallest suitable picture
size. 16mm pictures taken at 5000
frame/sec require a minimum film
speed of 38 meters per second.

6. In order to make full use of the
flame pictures the angular position of
the crankshaft during the exposure had
to be known. Similarly, the gas pres-
sure in the combustion chamber had to
be known at the same angle and in the
same explosion for each picture.

7. Simplicity of construction was an
important consideration that need not
be expanded upon here.

Of the optical systems available at
the time, the system suggested by Wed-
more2 seemed more nearly to fulfill
the qualifications than any other. A
camera incorporating these principles
was built into the flywheel of the engine
and is shown schematically in Fig. 5.
Light from the combustion chamber, D,
passed through the quartz window, F,
and was reflected by the stellite mirror,
H, into a stationary field lens, I, (a
Zeiss Opal Tessar). The principal plane
of the field lens was in the combustion
chamber. The beam of parallel rays
formed by the field lens passed through
each of a series of small lenses, M, as
they were moved through this beam of
light by a large circular disc attached
to the crankshaft and rotated in a plane
perpendicular to the plane of the paper.
Light from the series of lenses, M, was

reflected by a corresponding number of
right-angle prisms, N, also mounted on
the disc and located one behind each
small lens as shown in Fig. 5. Images
of the flames inside the combustion
chamber were formed upon the film,
P, which was held against the inside
surface of the rim of the disc by centrif-
ugal force. With such a system, the
image of a stationary object in the
combustion chamber remains at rest
with respect to the moving film (except
for a slight twisting motion) despite the
motion of the 30 small lenses. The
duration of exposure of each picture
was controlled by varying the width of
the stationary aperture, O, which was
close to the film and acted like a focal-
plane shutter. Another shutter, K, was
provided with the necessary actuating
mechanism so that exposure would take
place through only one revolution of the
disc.

The moving lenses were f/2 motion
picture camera objectives purchased
from the Eastman Kodak Co. The
focal lengths were closely matched, but
slight differences could be compensated
for by individual adjustment of the
position of each lens in the large disc.
The lenses were spaced 2.4 crankshaft
degrees apart, therefore 5000 frame/sec
could be obtained at an engine speed
of 2000 rpm and adequate exposure ob-
tained by adjusting the focal plane
shutter to give an exposure of 2.2 crank-
shaft degrees for each picture or 91 -|%
of the time between frames.

It is interesting in this connection to
calculate the amount of light lost in
this optical system. The stellite mirror,
H, Fig. 5, scattered about one-half the
light incident upon it. The amount of
light lost by Fresnel reflections at the
glass-air surfaces of the rest of the optical
system may be approximated from the
equation

where t is the total transmittance if

F. W. Bowditch: Research Photography

477

NON-KNOCKING

KNOCKING

ANGLE

-0,2

+ 2,2

+ 4.6'

Fig. 6. Full-view flame pictures which distinguish between knocking and non-
knocking combustion; four frames on left are before top dead center, and four frames
on right are after top dead center.

Fig. 7. 1939 Cadillac engine with quartz-window heads on left bank.
478 December 1952 Journal of the SMPTE VoL 59

absorption is neglected, n is the refractive
index of the optical glass, and k is the
number of glass-air surfaces. Since the
refractive indexes of optical glass in
common use lie between 1.5 and 1.7,
the average value of (n — l)2/(w ~h I)2 is
about 5% and the transmittance can
be computed with reasonable accuracy3
as / = (0.95)*.

The high-speed camera optical system
consisted of 16 glass-air surfaces since
both the field lens and the moving lenses
were multi component lenses. The
amount of transmitted light, therefore,
through the lens system and prisms
amounted to 44% of the incident light
not considering that lost at the stellite
mirror. Therefore, since about 50%
of the light was lost at the stellite mirror,
the approximate total transmitted light
was about 22% of the incident light.
If all the glass-air surfaces had been
coated, as is now current practice, the
approximate total transmittance would
have been about twice as much or
44%. The present-day Eastman High-
Speed Camera Model III, a rotating-
prism type camera, having a coated
Ektar lens and an uncoated prism can
be used without the large stellite mirror
mounted over the engine head and the
transmittance of this optical system is
approximately 83%. The older ERPI
Camera (Electrical Research Products,
Inc.) with uncoated optics, another ro-
tating-prism type of camera, without the
engine stellite mirror had a transmittance
of about 73%.

Since the ERPI exposure time
amounted to about 25% of the time
between frames and the engine camera
to about 90% of the time between
frames, the total amount of light reach-
ing the film per frame at the same
frame speed in the two cameras was
about the same due to the total trans-
mittance difference of the two cameras.
Experimentation with an ERPI camera
since the engine camera was built has
shown that even though the flame front
moved about three-and-one-half times

as far per exposure with the engine
camera as it did with the ERPI camera,
photographs of about equal definition
were obtained with the two cameras.
This apparent anomaly may be at least
partially explained by the distortion
of the images in the rotating-prism
cameras due to the motion of the prisms.

Returning to the combustion photo-
graphs obtained with the engine high-
speed camera, unrestricted views of
nonknocking and knocking explosions
were taken. The knocking explosion
pictures revealed in a most striking
manner the occurrence of spontaneous
ignition in sections of the unburned
charge well ahead of, and completely
separated from, the advancing flame
front. Figure 6 illustrates this difference
between normal or nonknocking com-
bustion and knocking combustion.

From similar pictures and correspond-
ing pressure records Drs. Withrow and
Rassweiler4 were able to sort out pressure
changes due to combustion from those
due to piston motion on the pressure
records and found very important
relations between per cent of pressure
rise and per cent of fuel-air mixture
burned. They were also able to deter-
mine the effects of changes in mixture
ratio, spark position and throttle opening
upon the combustion process — all very
important to the operation of our modern
automobile engines.

In 1939 interest was revived in a
combustion phenomenon known as
"after-running" (tendency for engines to
continue running at very low speeds
after ignition has been shut off). At
this time a 1939 V-8 Cadillac engine was
made available to these Laboratories
and quartz windows were mounted on
the left bank affording an unrestricted
view of the combustion chambers in
these four cylinders. This engine with
the quartz windows in place is shown in
Fig. 7. This engine may be familiar
to the reader since it was later exhibited
at the New York World's Fair.

In this investigation it was necessary

F. W. Bowditch: Research Photography

479

ii j« • H H

Fig. 8. Flame pictures of combustion in cylinder four of Cadillac window engine
during after-running; engine speed 260 rpm; throttle partially open; ignition spark
cut off; compression ratio 5:1; 60-octane secondary reference fuel; intake at top
and exhaust at bottom of each picture; 18 successive frames taken at rate of 1140
frames per second.

to obtain photographs of consecutive
explosions as they occurred in the engine.
Therefore it was not possible to use the
high-speed camera principles as outlined
by Wedmore and used in the previous
window engine since the old engine
camera was capable of taking pictures
of only one explosion. The ERPI
high-speed camera was used. In this
camera the field lens focuses the image
on the continuously moving 16mm film.
Between the lens and the film a glass
plate, or two-sided prism, is rotated in
such a way that the image is made to
move with film. In order to assure
complete synchronization of the film
and the image, a single motor is used
to drive both the film and the prism.
A complete discussion of the operation
of this camera may be found in the
literature.5

Eastman Kodak Super XX film and
its standard developing procedure were
used. Speeds were about 1150 frame/

sec and engine speeds were approxi-
mately 260 rpm. The engine ignition
system was shut off. Photographs were
taken of two adjoining combustion
chambers simultaneously with no effort
being made to determine the crankshaft
angular position for each photograph.
Figure 8 is an example of the photo-
graphs obtained for one explosion in one
of the combustion chambers. This
investigation revealed the important
fact that "after-running" was not due
to hot spots in the combustion chamber
since consecutive explosions showed that
combustion was never initiated at the
same point in the combustion chamber
in any two explosions. The exact
mechanism of this phenomenon is still
not known.

The investigation of autoignition (igni-
tion by means other than the spark plug
discharge) was reopened in 1943. At
that time interest in the problem was
quite high because of a general occur-

480

December 1952 Journal of the SMPTE Vol. 59

rence of field complaints. For this
investigation the original full-view win-
dow engine (see Fig. 4) without the
camera attachments was used. The
ERPI camera was used again with
16mm Super XX motion picture film
since photographs of consecutive explo-
sions were again required.

It was necessary in portions of this
investigation that the angular position
of the crankshaft for each photograph
be known since the photographs were
to be used in connection with pressure
card data. A double-lobed cam was
used on the distributor so that the spark
plug (which was in the field of the
camera) would fire twice, once to initiate
combustion and again 90 crank-angle
degrees later for a timing mark. These
spark discharges did not always appear
on the film because they would some-
times occur entirely during the two-
thirds of the time the film was not being
exposed. By using the built-in ERPI
timer and those spark discharges which
were available, it was possible to de-
termine the average time in crank-angle
degrees per frame and so determine
the angular position for each photo-
graph. Similar calculations were made
on the time axis of the pressure records
so that the photographs and pressure
records could be related. It is interest-
ing to note that the speed of the engine
could be found more accurately from
the flame photographs than with the
available engine instrumentation due
to the electrical timer built into the
ERPI.

For orientation purposes the metal
frame around the quartz window was
illuminated with 120-w photoflood
lamps. These lamps were used at
shallow angles of incidence to the head
of the engine so that the combustion
chamber itself was not illuminated.
This frame outline on each photograph
provided the necessary reference points
for the orientation of the random centers
of ignition which occur during auto-
ignition.

In this autoignition investigation
various types of engine deposits were
accumulated with a full metal head on
the engine. The engine was then
stopped and the quartz head substituted
for the metal one. Pictures of the
combustion process in the presence of
the deposits were taken shortly after
the engine was restarted. Ordinarily
the engine with the quartz head could
be run for only short periods of time
with deposits in the combustion chamber
since the deposits became detached
from the combustion chamber walls
and were deposited on the quartz
window. By taking photographs of
consecutive explosions as they occurred
in the presence of various deposits, some
very important effects of combustion
chamber deposits upon the combustion
process were determined.

Interest was again revived in the
subject of autoignition in 1951 since
autoignition rather than knock became
one of the most important considerations
in attempting to increase the perform-
ance of automobile engines. The origi-
nal full-quartz-head window engine,
now 21 years old, was again used at the
beginning of this investigation which is
now in progress.

Four changes have been made in the
procedure used in 1943. The first
was the substitution of an Eastman
Model III High-Speed Camera for the
older ERPI camera. The basic prin-
ciples of operation of the two cameras
are the same but improved methods of
operation are incorporated in the newer
camera. A complete description of this
camera may be found in the literature.6

Second, since stiffening blocks had
been added to the top surface of the
window frame, the angle of incidence
of the illumination from the flood lamps
used to light up the frame around the
quartz window had to be increased.
In so doing some of this light illuminated
portions of the combustion chamber
making definition of the combustion
process in these areas difficult. There-

F. W. Bowditch: Research Photography

481

Fig. 9. 16mm frame showing the flywheel at the right
and the fluorescent window frame.

fore, the top of the window frame was
painted with blue fluorescent sign paint
and illuminated with ultraviolet light
from three General Electric 100-w
E-H4 projector flood lamps operated
on direct current using filters similar
to Corning filter color specification 739
which confined most of the illumination
to ultraviolet wavelengths. This method
gave sufficient visible light from the
window frame but did not affect the
pictures of the combustion process.

The third major change from pre-
vious operating procedure was the use of
Eastman Kodak Linagraph Pan 16mm
film in place of Eastman Kodak Super
XX film. This was done because of
the exceptional blue sensitivity of this
new film and the predominance of blue
light given off by the combustion process
allowing shorter exposure times to be
used.

The fourth and perhaps most im-
portant change in procedure was the
method used to determine the angular
position of the crankshaft at which each
picture was taken. This was done by
replacing the //2.7, 63-mm focal-length
lens with which the camera was equipped
with an //1. 9, 25-mm focal-length lens.
The shorter focal-length lens provided a
sufficiently great depth of focus so
that when the combustion chamber of
the engine was in focus the flywheel of
the engine which was about seven inches
further from the camera than the com-
bustion chamber remained well enough
in focus so that the degree divisions on
the flywheel could readily be seen.
Even though the shorter focal-length
lens reduced definition, the photographs
were sufficient for this study. The rim
of the flywheel was painted a dull black
and the degree divisions and numbers
white. At frame speeds of 2000 frame/

482

December 1952 Journal of the SMPTE Vol. 59

Fig. 10. Eastman Camera and CFR L-head engine fitted with quartz window.

sec and flywheel rim velocities of about
47 ft/sec the numbers and degree
division marks were sufficiently clear
that readings to the nearest one-half
crankshaft degrees could be made on
each picture. An example of the results
obtained by using the fluorescent frame,
the Linagraph Pan film and the short
focal-length lens is shown in Fig. 9.

When the opportunity presented itself
in 1951 a newer engine more nearly
like the modern automobile engine was
equipped with a quartz head (Fig. 10).
The work on autoignition was trans-
ferred to this engine with three alterations
in the photographic procedure. First,
since the head of the engine was un-
obstructed, photoflood lamps could be
used at shallow angles of incidence to
illuminate the quartz frame. Second,

the flywheel division marks were made
narrower and longer allowing the crank-
shaft angular position for each frame to
be determined within 0.1°. The third
change in photographic procedure was
brought about by the desire to obtain
both motion pictures of the combustion
process and, simultaneously, oscillo-
scope pictures of the pressure records of
the combustion processes. A Fairchild
oscilloscope camera was used to take
the oscilloscope pictures and, in order to
relate the pressure records to the corre-
sponding engine combustion process, both
a small incandescent lamp in the oscillo-
scope camera and a 40-w incandescent
lamp in the field of view of the high-
speed camera were flashed simul-
taneously. By having one explosion
related, the remainder of the two films

F. W. Bowditch: Research Photography

483

FRAME NO,

CRANK AN6LE

7 8

mmm^ r*

L*% m %if m S

t s

»20 IDC 20 48

CRANK ANGLE DEGRESS

100

Fig. 11. Flame pictures and corresponding pressure card of preigniting explosion;
engine speed 900 rpm; throttle fully open; spark advance 16 deg before top dead
center; air-fuel ratio 13:1; compression ratio 6.8 : 1; 70-octane number reference fuel.

could be correlated readily. Figure 11
illustrates the type of record obtained by
this process. This engine and photo-
graphic procedure is being used at the
present time as a tool in the continuing
research on our modern automobile
engine.

References

1. L. L. Withrow, and T. A. Boyd,
"Photographic flame studies in the
gasoline engine," Ind. Eng. Chem., 23:
539-547, May 1931.

2. E. B. Wedmore, "A novel high-speed

camera," J. Sci. Instr., 4: 345-347,
1927.

3. A. R. Greenleaf, Photographic Optics,
Macmillan, New York, 1950, pp. 49-
50.

4. G. M. Rassweiler, and L. L. Withrow,
"Motion pictures of engine flames
correlated with pressure cards," SAE
Jour. (Trans. \ 42: 185-204, May 1938.

5. F. E. Tuttle, "A non-intermittent high-
speed 16mm camera," Jour. SMPE, 21:
474-477, Dec. 1933.

6. J. L. Boon, "The Eastman high-speed
camera, Type III," Jour. SMPE, 43:
321-326, Nov. 1944.

484

December 1952 Journal of the SMPTE Vol. 59

Accuracy Limitations on
High-Speed Metric Photography

By AMY E. GRIFFIN and ELMER E. GREEN

Parameter limits in high-speed camera design and physical characteristics
of photographic images limit the assessment accuracy of high-speed metric
film records. The errors in film measurements range from 2 to 75 microns.
Proper design of field instrumentation is required to minimize effects of
reading errors in a measurement system for ballistic data.

Uses of Metric Cameras

The measurement system on the
ground ranges at the U.S. Naval Ord-
nance Test Station, Inyokern (NOTS),
was designed primarily to obtain ballistic
data on rockets and guided missiles.
High-speed photography, which is here
defined as photography at more than 500
frame/sec, is a useful tool for studying
missile flight phenomena such as flame
characteristics but is seldom applicable
to the study of ballistic parameters which
are derived from missile trajectory and
attitude data. High-speed cameras are
not useful for these purposes because,
in general, their accuracy limitations are
too severe to permit their use at their
high frame rates as metric instruments,
i.e. instruments from which data such
as velocity, acceleration and direction
of motion (which are usually obtained

Presented by Amy E. Griffin on October
9, 1952, at the Society's Convention at
Washington, D.C., by Amy E. Griffin and
Elmer E. Green, Assessment Div., Data
Reduction Branch, U.S. Naval Ordnance
Test Station, Inyokern, China Lake, Calif.

by differencing successive position de-
terminations) can be obtained.

If an unsuccessful missile flight is
caused by factors inducing vibrations
or moments resulting in instability, the
first photographic evidence of this may
be some physical change in the missile
such as the breaking of a stabilizing
fin. To pinpoint the time of this
occurrence photographically to desired
accuracy may require frame speeds of
1000 per sec or higher, but a mere de-
termination of the moment of failure is
inadequate for flight analysis. In
addition to knowing the exact time of
failure it is necessary to study closely the
behavior of the missile previous to this
time to determine whether the fin was
substandard or whether the failure was
caused by unexpected stresses on the
fin. If the latter is the case, data are
required to determine whether the un-
expected stresses were caused by aero-
dynamic forces larger than anticipated
or by inability of the missile to achieve
flight stability under the anticipated
conditions.

December 1952 Journal of the SMPTE Vol. 59

485

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December 1952 Journal of the SMPTE Vol. 59

The photographically obtainable data
which are required to determine the
cause of failure are the missile velocity,
acceleration, direction of motion and
attitude. From the difference between
the attitude of the missile and its direc-
tion of motion can be determined the
direction in which aerodynamic forces
are applied to the fins. From the
missile velocity and acceleration can be
determined the magnitude of the forces.
The direction of the force may be
needed to an accuracy of ±0.1° or
better. The acceleration may be re-
quired to an accuracy of ±1 G.

To obtain free-flight data with the
above accuracy at rates of 1000 frame/
sec would require impossible accuracies
in position determinations. Random
errors of ±0.00001 ft in position would
result in an error of ±1 G in accelera-
tions obtained by differencing of position
data from successive frames.

Using specially designed cameras, it
is often possible to hold random errors
in missile position determinations to
approximately ±0.04 ft. When position
determinations are held to this accuracy,
frame rates in the order of 20 per sec
result in acceleration accuracies of ±1
G. If long focal length lenses are used
with these special cameras or if the
cameras can be placed close to the flight
line, random missile position errors in
the order of ±0.001 ft can be obtained.
Frame rates of 90 per sec can be used
with this position accuracy to obtain
±1 G acceleration accuracy. This
accuracy, however, can be achieved
only with such cameras as the Bowen
Ribbon Frame camera and then only
if the film can be read to an accuracy
of ±2 microns.

Camera Parameters

Some of the cameras in use at NOTS
are standard high-speed machines but
others such as the Bowen ribbon frame
cameras1 and Askania Cinetheodolite2
were originally designed for metric pur-
poses. Table I compares their operating

characteristics. The table does not
include all cameras in common use at
NOTS but merely gives single examples
of each type. Likewise, only the most
frequently used lens-and-shutter combi-
nations are given.

These cameras differ widely not only
in their ' operating characteristics but
in the accuracy limits for data obtained
from them. In determining the ac-
curacy limitations of a camera and
consequently its usefulness as a metric
tool, the following factors are considered :

1. resolving power,

2. accuracy with which the lens and
film orientation can be determined, and

3. accuracy with which the time of
exposure of the missile can be deter-
mined.

Resolving power is considered here
as the resolving power of the lens and
film combined when photographing
missiles under usual lighting. The
resolving power is then defined as the
reciprocal of twice the diameter of the
finest line that can be resolved on the
film under these conditions. Expressed
mathematically

R = \/2w

(1)

where R is resolving power in lines per
millimeter and w is the width of the line
in millimeters.

This definition is essentially in
agreement with standard methods of
determining resolving power with the
exception that this is the resolving power
under ordinary medium contrast, not
with high contrast. Since high contrast
in the negatives is rarely possible, the
use of a resolving power based on that
condition is invalid.

Resolving power is linked to accuracy
in missile position in the following way.
It has been experimentally determined
that a line of medium contrast to the
general background can be bisected to
an accuracy of about 1/20 its width.
Thus (using standard film-measuring
devices) an operator can bisect a ref-
erence line and the missile line on the

Griffin and Green: Accuracy Limitations

487

film and record their coordinates. If
both the reference line and the line on
the missile are the finest lines resolvable,
the standard error in the distance from
the reference to the missile will be equal
to A/2/20 the width of each line (this
allows for errors on both measurements).
Expressed mathematically

Af = V2Z0/20 (2)

where Af is the standard reading error
in millimeters on the film and w again
is the width of the finest resolvable line
in millimeters.

By substitution of Eq. 1 in Eq. 2

Af = V2/40# (3)

If the camera is to be used as a track-
ing camera, Eq. 3 is sufficient because
if the resolving power is too low to give
sufficient reading accuracy, a longer
lens can be used so that reading errors
result in correspondingly less error in
missile position determination.

If the camera is not used to track the
missile but has a fixed coverage, then
reading accuracy must be considered
in terms of the coverage desired with
this camera. Essentially, the data de-
sired are acceleration values, but since
these are obtained by differencing two
velocity values which in turn are ob-
tained by differencing two position
values, it is always necessary to obtain
two more frames including the missile
than the number of acceleration values
desired from this one camera. Also
the relation between reading accuracy
on the film and acceleration accuracy
must be defined.

If only position errors are considered
it can be shown that

where As is the standard position error

of the missile in feet,
A a is the standard acceleration

error in feet per second

squared,
As is the standard position error

of the missile in feet, and

T is the time between successive

frames in seconds.

But if the width of the frame in the
direction of rocket travel is Wf in milli-
meters and the distance in feet in space
that this film covers is Ws, projecting
film readings into space:

Wf/W. = Af/A.

(5)

Substituting Eq. 5 and Eq. 3 in Eq. 4 :
Aa = V3 W./2QWfRT* (6)

Ws, the distance covered along the
trajectory, is a function of the focal
length of the camera and the distance
from the camera to the missile, but since,
n general, the focal length and camera
distance can be varied, it is more useful
to consider the distance in terms of
the coverage desired. If the average
velocity of the missile as it passes the
camera is F and S is one less than the
number of frames in which the missile
is exposed, then:

W. = VST

(7)

where T again is the time between
successive frames.

If Eq. 7 is substituted in Eq. 6

A. = V3~ VS/20 WfRT (8)

Since there must be two more frames
than the number of acceleration values
and S is always one less than the number
of frames in which the missile is exposed,
S is always one greater than the number
of acceleration values. If Eq. 8 is
written in terms of both the acceleration
error and the number of acceleration
values desired and converted to G's,

Aa/S = V3 F/640 WfRT (9)

Since Frame Speed (F.S.) is the re-
ciprocal of Ty the time between frames

Aa/S = V3 VF.S./640 WfR (10)

If the acceleration error (Aa) is re-
quired to be less than one G and if only
one acceleration value is required
(which makes S = 2), for a velocity of
1000 fps and a resolving power of 10

488

December 1952 Journal of the SMPTE Vol. 59

Table II. Errors of Missile Exposure Time.

Camera type

Shutter type

Random
Modifications to original errors in time,
camera /*sec

Askania

Mitchell
Bowen

General Radio
Fastax

Venetian blind

Rotating sector
Rotating drum slit

None (Edgerton Flash)
Rotating prism

Camera dials illuminated by
Edgerton Flash Lamps
Binary timing
Finer slits in drum; 1000-
cycle timing pulses on film

1000-cycle timing pulses on
film

3000

300
3

0.1
20

lines/mm, the highest frame speed over
which acceleration data can be obtained
with 35mm film would be 70 frame/sec.

In general, 5 to 10 acceleration values
are desired from each camera. As a
result, the Bowen cameras are used with
the centerline of the 125-mm frame set
approximately parallel to the portion of
trajectory to be covered. On Bowen
Film R = 10 lines/mm under most
conditions. This value of R is low
because of the movement of the missile
image and the film during exposure.

Aa/S = V X F.S. /452,500

(11)

If Aa is 1 G, S = 10 and V = 1000,
the highest usable frame speed is 45
per second. Data are usually obtained
at the rate of 10 per sec or 30 per sec
from Bowen cameras since missile ve-
locities may be larger than 1000 fps.

But resolving power is not the only
factor determining the accuracy of
acceleration values. Under many condi-
tions, it is necessary that the camera
track the missile, so the accuracy with
which the orientation of the lens and
film can be determined is also important.
With present camera mounts these
orientations can be determined no
better than ± 1 minute of arc and since
high missile velocities require that the
cameras be located some distance from
the flight line in order that the operator
can track the missile, these cameras

have random errors in missile position
of the order of 1 to 3 ft. This invalidates
the use of high frame rates for ballistic
purposes.

Even for cameras which do not track
the round, it is necessary to determine
the camera orientation to a fairly high
accuracy because errors in this orienta-
tion introduce bias errors in the data.
The ± 1 minute of arc accuracy obtain-
able is sufficient to make bias errors
inconsequential.

Besides resolving power and camera
orientation there are still errors in the
time of exposure of the missile. Con-
sider the following example: If a
missile is traveling 1 000 fps, to determine
its position to ±0.01 ft the time of missile
exposure must be known to the nearest
10 Msec.

The errors in time of exposure of the
missile as best determined for the
cameras in common use are given in
Table II.

In general these errors in time of
missile exposure have a random error
effect on the accuracy of velocity and
acceleration data. When cameras are
used to track missiles, timing errors are
inconsequential if the tracking is smooth.
The 3000-Aisec error in Askania timing
does not affect the accuracy of velocity
and acceleration data if the operator
is able to keep the missile in the center
of the frame. But if he is not able to
do so, the tracking error measured on

Griffin and Green: Accuracy Limitations

489

the film may not be the true tracking
error at the time of exposure of the dials
from which the azimuth and elevation
angles of the camera are determined.
If the angular error in tracking is greater
than 3° per sec, timing errors appreciably
affect the accuracy of the data.

A study of Table II indicates that in
some cases the time of exposure can be
determined very precisely. Often this
cannot be done without studying the
camera design and measuring some of
its components. For a camera such
as the Bowen it is necessary to obtain
the dimensions of the shutter drum,
shutter slit, and film drum and to
measure the revolution rate of the shutter
drum, the film speed, and the position
of the missile in the film. This and
other corrections to Bowen Cameras
have been investigated previously.3

These, then, are the tools available
for recording photographic data of
missile flights. The Bowen and Askania
cameras are used to obtain the greater
part of metric data. The higher speed
cameras are relegated to uses such as
determining flame characteristics, for
which they are better fitted. Data
describing high frequency changes in
missile behavior can be obtained only
through use of metric electronic equip-
ment. Since electronic equipment can-
not be used under many conditions, it is
essential that each camera be used in
such a way that the utmost accuracy
from that camera is obtained and the
highest significant frame rates can be
used.

Instrument Usage

The problem of using each camera at
its maximum efficiency by making use of
its good points and minimizing its weak
points has been met at NOTS in the
following ways:

1. Determine the sources of errors in
each camera.

2. Modify cameras where possible to
eliminate errors.

3. Determine the magnitude of those

errors that cannot be eliminated con-
veniently by modification.

4. Use the camera in a location and
manner which minimize the effects of
remaining errors.

5. Have sufficient records to make it
possible to overdetermine each trajectory
point.

6. Apply statistics to obtain a satis-
factory approximation of the trajectory
point in question.

7. In terms of the solution obtained in
item 6 above check the determination
of errors from each camera (item 3)
and also obtain an evaluation of the
test data.

8. On a long term basis, design
cameras which will have the character-
istics required.

The development and use of Askania
Cinetheodolite cameras exemplify the
method of accounting for camera errors.
The cameras were built and used by the
Germans to obtain aeroplane flight data.
For this use neither high frame speeds,
high shutter speeds, high tracking rates
nor good synchronization between the
dials and the picture was needed.

In planning to use these cameras for
missile flight data it was immediately
obvious that the tracking rates would
have to be increased. This was accom-
plished by eliminating the gear-drive
making them free-sliding on their bear-
ings. Since exposure of the dials in-
dicating camera orientation was not well
synchronized with the main shutter,
better synchronization was achieved
by illuminating the dials with Edgerton
flashlamps whose discharge was timed
to coincide as far as possible (±3 msec)
with the opening of the main shutter.
The high illumination and short exposure
of the Edgerton flashlamps also effectively
stopped the apparent motion on film
of the azimuth and elevation dial read-
ings.

With these modifications Askanias
were installed as an integral part of the
range instrumentation system. To mini-
mize reading errors, the cameras were

490

December 1952 Journal of the SMPTE Vol. 59

placed as close to the flight line as the
tracking rates and safety conditions
would allow, and enough cameras were
used to insure that at least three cameras
would be photographing the missile at
all times.

In reduction of data a method of least
squares is used which permits the combi-
nation of data from any number of
cameras simultaneously to obtain a
solution. This method2 permits weigh-
ing the data from each camera relative
to its distance from the missile. The
solution of missile position so obtained
is, on the average, nearer to the true
position than any other solution that
can be computed. Since this solution
minimizes the residual error from each
camera, analysis of the errors from
several flights permits a determination
of the magnitude of the errors from each
camera.

Checking the errors so determined
over several tests indicated that some of
them were not truly random. This led
to an investigation of the azimuth dials
and bearings and to the discovery that
the dials were eccentric relative to the
bearings. As a result, tests were de-
signed to measure the eccentricity so
its effect could be eliminated from the
data during computation. At the pres-
ent time, with all known corrections
applied, missile position can be deter-
mined to an accuracy of ±3 ft. This
invalidates data obtained at high frame
rates so the 4 per sec frame rate of the
Askanias is adequate. For this reason
they are used to cover those portions of
the trajectory where changes in velocity
and acceleration are slow, such as the
afterburning flight of the missile. For
documentary purposes, a Mitchell, East-
man High-Speed or Fastax camera
may be used alongside the Askania at
high frame rates to obtain documentary
coverage simultaneously with the As-
kania data.

Experience in the use of Askania
cameras has been incorporated in speci-

fications for future tracking equipment
with requirements as follows:

1. construction of a mount on which
any one of several cameras can be
mounted,

2. motor drive for the mount,

3. higher accuracy in the mount,

4. electrical circuitry permitting the
starting of each camera automatically at
a predetermined time in the missile
flight,

5. longer and "faster" lenses, and

6. pulse operated or synchronously
driven shutters.

The accuracies obtained with present
Askania cameras using 24-in. lenses
require only low reading accuracy. A
reading error of 0.060mm results in an
error of only 10 sec of arc in the determi-
nation of the direction of the line from
the camera to the missile which, if the
missile were 10,000 ft away, would
result in a 1-ft position error. If future
cameras are equipped with longer
lenses, accuracies in missile position
made possible with higher accuracies in
the mount can be obtained with no
greater demand on reading accuracies.

A study of the development of the
Bowen ribbon-frame camera shows
changes in its use and accuracy similar
to that resulting from Askania use.
Since this camera was designed origi-
nally for missile acceleration data, the
changes have been more of degree than
kind. Its present use and accuracy are
limited principally by the resolution of
the lens-film combination. Studies are
underway to develop an //3.5 lens with
high resolving power for this camera.
Since an //3.5 lens would permit ex-
posure times of the order of 10 ^isec,
blur on the film caused by image and
film movement would be greatly lessened.
It is expected that resolving powers of
20-30 lines/mm will be possible under
these conditions.

Recently a 70mm camera has been
developed4 which can record at a rate
of 450 pictures per sec. The film does

Griffin and Green: Accuracy Limitations

491

not move during the exposure so the
resolving power of this camera may be
high enough to validate data obtained
at a 450 per sec rate.

In conclusion, the use of high-speed
cameras for metric purposes illustrates a
common experience — equipment well
suited for one specific purpose may be
entirely inadequate for a similar purpose.
The extremely high frame speeds pos-
sible with the Fastax and Eastman
High-Speed cameras are usually useless
for metric ballistic purposes because of
the accuracy limitations of the cameras
and film. It has been necessary to
design metric cameras with these ac-
curacy limitations in mind and use
them in ways that minimize their errors.
Greater accuracies can be achieved
only if emulsions and lenses can be
developed which permit the use of shorter
exposure times and which at the same
time possess higher resolving power.

References

1. T. J. Obst and J. A. Clemente, "The
Bowen ribbon-frame cameras,"
NAVORD Report 1273, NOTS 343,
U.S. Naval Ordnance Test Station,
Inyokern, Calif., Jan. 15, 1951. See
also, for general description: E. E.
Green and T. J. Obst, "Bowen ribbon-
frame camera," Jour. SMPE, 53:
515-523, Nov. 1949.

2. John Titus, Mary Driggers and
Laurence Minvielle, "Methods of
measurement and computation to de-
termine trajectory data from Askania
Cinetheodolite records," NAVORD Re-
port 7907, NOTS 433, U.S. Naval Ord-
nance Test Station, Inyokern, Calif.,
Sept. 10, 1951.

3. John Titus and Amy E. Griffin, "A
method for the reduction of trajectory
data from CZR-1 and RC-2 Bowen
ribbon-frame cameras," NAVORD Re-
port 7967, NOTS 537, Naval Ordnance
Test Station, Inyokern, Calif., Apr. 30,
1952.

4. Charles T. Lakin, "The 70mm test
vehicle recorder," NOTS Technical
Memo No. 7740, U.S. Naval Ordnance
Test Station, Inyokern, Calif., July 25,
1952. See also: Charles T. Lakin, "The
70mm test vehicle recorder," presented
on October 9, 1952, at the Society's
Convention at Washington, B.C., and
planned for early publication in the
Journal.

Discussion

Dave Miller (Battelle Memorial Institute):
I would like to get some confirmation of
the apparent fact that your Askania data
are correct within one to three feet, is
that correct?

Mrs. Griffin: Yes. However, this de-
pends on how far it is from the camera to
the missile.

Mr. Miller: How far?

Mrs. Griffin: Within 10 or 15 thousand
feet. The random errors in the azimuth
and elevation angles measured with
Askania cameras at the present time are
of the order of one minute. There are
also eccentricity errors in these cameras
which can be corrected for but they seem
to change with time, which makes it
difficult to do so.

Mr. Miller: I wonder whether you
could not release a number of flares with
parachutes, so that several of them would
always be within the field of view. They
should move quite slowly, their motion
should be substantially constant, and
their motion could be computed, so that
the positions of such flares as seen in the
photographs could be used as a basis for
determining the changes in azimuth and
elevation, eliminating the need for de-
pendence on the scales provided on the
mounting of the camera.

Mrs. Griffin: We, at Inyokern, are right
beside the Sierra Nevada Mountains.
I don't know whether you have knowledge
of the wavefronts there, but this region is
where they do their experimental sail-plane
flying. The wind velocities are of the
order of 60 mph. They may change with-
in 1000 ft and go in the reverse direction.
I don't think it is practical.

Mr. Miller: Then possibly another site
might be considered favorably.

492

December 1952 Journal of the SMPTE

Vol. 59

High-Speed
Cine-Electrocardiography

By JOSHUA J. FIELDS, LOUIS FIELDS, ELEANOR GERLAGH
and MYRON PRINZMETAL

This paper describes a method of using the high-speed camera in medical
research on heart disease. Normal and abnormal human and animal hearts
are photographed at high speed simultaneously with the electrocardiograph
recording, to ascertain and to study the conditions revealed by similar electro-
cardiograms of human patients.

FNE OF THE most useful tools for
studying the motion of the heart is the
high-speed camera. For several years
we have been taking slow motion pictures
of the intact, beating heart of animals,
before and after the experimental pro-
duction of certain types of heart dis-
orders. The magnification in time and
detail has revealed much about the
contraction not only of the whole heart
but of the individual muscle fibres as
well, in both normal and abnormal

Presented on October 10, 1952, at the
Society's Convention at Washington, D.G.,
by Ethel Foladare for the authors. This
work is from the Institute for Medical
Research, Cedars of Lebanon Hospital,
4751 Fountain Ave., Los Angeles 29,
Calif., and the Department of Medicine,
University of California Medical School,
Los Angeles, Calif. This study was aided
by grants from the L. D. Beaumont Trust
Fund, the Blanche May Memorial Fund,
the Margaret Mayer Fund, L. Spitz, I.
Berlin and E. Mannix.

cardiac conditions. Careful analysis of
these motion pictures has yielded a great
deal of information concerning the mech-
anism and nature of heart action.

However, the clinical diagnosis of
heart disease depends to a great extent
upon what the electrocardiographic
tracing reveals. In order to apply
what we learned from the motion pic-
tures to patients with heart disease, it
was necessary to correlate the me-
chanical events of the heart with the
electrical events. This meant, of course,
recording the heart motion and the
electrical trace simultaneously, and on
the same film. In this way, corre-
sponding mechanical and electrical events
could be analyzed. After many trials
and errors, a suitable technique was
devised.

Procedure and Equipment

Figure 1 illustrates diagrammatically
the relative positions of the equipment
used. The camera is focused directly

December 1952 Journal of the SMPTE Vol.59

493

SIDE VIEW

DIRECT-WRITING EGG.

TOP VIEW

HEART

CAMERA

Fig. 1. Diagrammatic representation of the arrangement of equipment used for
photographing the heart and electrocardiogram simultaneously. Note that the
electrocardiogram is filmed by photographing its reflection in a mirror placed equi-
distant from the heart and the surface of the electrocardiographic apparatus.

on the heart at such a distance that the
part of the heart to be studied fills
approximately the left two-thirds of the
field. The electrocardiographic ma-
chine is placed well below the level of
the heart and is mounted on a jack so
that adjustments in height are possible.
The electrocardiographic machine and
a first surface mirror are moved into
position so that the reflected image of
the trace occupies the right one-third
of the field. The mirror image of the
electrocardiogram will be in focus only

if the distance from the surface of the
electrocardiographic machine to the
mirror is the same as the distance from
the mirror to the heart. The mirror
is mounted on a stand with a rack-and-
pinion gear for adjusting its height;
worm gears with a 100 to 1 ratio control
its rotation and angulation. In this
way, very fine adjustments in positioning
the mirror are possible. Since we
photograph the mirror image of the
electrocardiogram, an arrangement of
the circuits was made which inverts

494

December 1952 Journal of the SMPTE Vol.59

the actual tracings aiid thus corrects the
maged trace. f

Cameras. Two types of cameras were
used. A modified Bell & Howell
"70" Specialist camera with a speed
of 200 frame/sec was employed when
visualization of gross movements of the
heart was desired. The lenses used
with this camera were a 75-mm Pan-
Techar, //2.3, and a 100-mm Pan-
Techar, //2.3. For extremely detailed
analysis the Wollensak Fastax, 16mm
camera was used with a 4-in. Wollensak
lens, //3.2. The Fastax was used for
color pictures taken at 500, 1000 and 2000
frame/sec, and for black-and-white pic-
tures at 5000 frame/sec.

Electrocardiographic Equipment. An ink-
writing, dual-channel Brush Magnetic
Oscillograph was found to be most
suitable for recording the electrocardio-
gram. This machine has a paper speed
of 125 mm/sec which is five times faster
than the standard electrocardiographic
paper speed. Each complex was thus
magnified for great accuracy of analysis.
In addition to the two writing pens, a
time marker pen was installed at the
edge of the paper. A pip every j sec
produced by a synchronous motor pro-
vided the time reference.

Light Sources. In all high-speed photog-
raphy, the problem of a suitable light
source exists. In high-speed medical
photography, adequate light must be
combined with a minimal amount of
heat because one is dealing with living
tissue. Excessive heat, of course, is
injurious to tissue and precautions must
be taken to keep all experiments under
at least near-physiologic conditions.

For the Fastax pictures, a bank of from
7 to 20 General Electric 750-R lamps
was used on the heart. Usually two or
three of these focused on the electro-
cardiographic paper were sufficient.
These lights generate intense heat and

various attempts were made to over-
come this — heat-absorbing glass, water
cells, etc. However, in our setup, these
were all awkward and difficult to
manage. The simplest solution was to
use 50-ft rolls of film in the Fastax
camera and to turn on the lights after
the camera was started and turn them
off (by calculation) just before the film
ran through. In this way, perhaps
1 5-20 ft of film were underexposed but
the heart was subjected to the heat for
only a very short time — from less than
one second to a maximum of three and
a half seconds. It was not uncomfort-
able to hold the hand in the light field
for this period of time.

Pictures taken at 200 frame/sec
require less light; General Electric
RSP-2 lamps were used for this camera
speed. A bank of five lamps directed
at the heart from a distance of approxi-
mately 3 to 4 ft and one lamp on the
electrocardiographic paper at about
2 ft were sufficient for good color. The
heat problem was obviated by taking
continuous film runs of not more than
25 ft at a time. Thus again, the lights
were on for only a minimal length of
time and the heat to which the heart
was exposed was well within the physio-
logic limit.

For taking pictures of the beating
human heart, the precautions and limita-
tions which apply to photography of the
experimental animals were even more
strict. Thus we have been limited in
the number and choice of the patients
we have been able to study in this man-
ner. However, a new type of lamp was
loaned us recently through the kindness
of John H. Waddell of the Wollensak
Optical Co. This is the Fastlite, which
is a compact unit with a built-in water
cell. These lights have proved most
satisfactory, for they are less cumber-
some than the battery of hot lamps and
they give an extremely intense light
with a minimum of heat.

Fields et al.: Cine-Electrocardiography

495

PEN

TIPS

Fig. 2. Enlargement of 16mm frame photographed with the Fastax camera in
black-and-white at 5000 frames/sec. The heart is at the left and the electrocardio-
graphic trace is at the right. The ink-writing pens (indicated by arrows) have just
finished writing the electrical counterpart of the contraction of the heart from two
different leads.

Results and Comment

Figure 2 is an enlarged frame from
one of the motion pictures taken by the
technique of cine-electrocardiography.
The heart is on the left and the mirror
image of the electrocardiographic trace
is at the right. The pen has just
finished writing the electrical complex
which corresponds to the contraction
of the heart.

The apparatus used for positioning
the mirror and the electrocardiographic

machine makes it feasible to record
photographically any or all parts of the
electrical trace, i.e. one channel or two,
a narrow strip or a wide one. It is
also possible to vary the size and the
field of the trace.

The most satisfactory / stop for both
200-frame and Fastax pictures up to
2000 frame/sec was found to be 4.5.
This gives a fair depth of focus which is
necessary since we are dealing with an
object which has a field of motion of

496

December 1952 Journal of the SMPTE Vol. 59

about two inches in all directions. Also
at this aperture the relatively small
amount of light lost is well worth the
definition obtained in the pictures. At
a camera speed of 5000 frame/sec, the
lens is stopped down to //8 using the
same amount of light as for the slower
speed. In this way almost no loss in
definition occurs.

If meticulous care is taken in position-
ing the heart, mirror and electrocardio-
graphic machine, and careful attention
is given to the lighting, exposure and
focus, truly beautiful pictures result.
More important than esthetic considera-

tions, the films here described now make
it possible to demonstrate definite rela-
tionships between electrocardiographic
patterns and their mechanical counter-
parts. Although this technique has been
in use only a few years, it has already
yielded conclusive evidence confirming
or disproving a number of previous
theories concerning the mechanism of
common cardiac disorders. The pic-
tures can be studied repeatedly and thus
have proved to be a valuable scientific
instrument, for they reveal with fine
detail and clarity, action that is not
visible to the unaided eye.

Fields et al.: Cine-Electrocardiography

497

Optical Aids for
High-Speed Photography

By DAVID C. GILKESON and A. EUGENE TURULA

Several new series of highly corrected lenses for high-speed motion picture
and professional 35mm use have been designed with focal lengths ranging
from 3.7 mm to 2000 mm. Mirror optics have been used for the longer focal
length lenses. Particular optical design and fabrication problems are dis-
cussed with reference to mirror optics. Special optical devices to aid the
high-speed photographer are discussed.

N ORDER to meet the many needs of
professional users of 35mm motion
picture cameras, Fastax cameras, 35mm
still cameras and specialized applications
of these cameras, several new series of
lenses and aids have been developed.
High-quality optical performance was a
primary requirement because the lenses
are to be used to record and study a
variety of actions and instrument data
over a wide field, for tracking, and for
photographing and identifying distant
objects in detail. The number of ele-
ments used in the construction of the
lenses ranges from two to eleven (Tables
I— V). The number necessary to achieve
the performance desired is generally
dependent upon the performance, aper-
ture, and coverage requirements. The

Presented on October 10, 1952, at the
Society's Convention at Washington, D.C.,
by David G. Gilkeson and A. Eugene
Turula, Wollensak Optical Co., 850
Hudson Ave., Rochester 24, N.Y.

form and disposition of the elements
within the system are dependent upon
performance, aperture, coverage, space
considerations, and special effects de-
sired. With some exceptions, the num-
ber of elements used is no more than
necessary and sufficient to meet the
performance specifications of the user.
The exceptions are the Raptar tele-
photos (Table II). It was much more
important to have as short a back focus
as possible for mechanical stability. If
the back focus and general adaptability
requirements were not important, ach-
romatic doublets or triplets could have
been used, depending upon the focal
length.

The evaluation of lens performance
by photographic resolution measure-
ments has been well covered in previous
papers.4"10 Such a test, however,
measures performance of the lens-film
combination and the result depends
greatly on the methods, techniques and

498

December 1952 Journal of the SMPTE Vol. 59

Table I. Pro-Raptars

Table III. Mirrotel (Catadioptric Tele-

Focal
length

Diagonal Type and No. of
//No. coverage elements

)

Focal
length

Diagonal No. of
//No. coverage elements

25
35
50
75
101
152

mm
mm
mm
mm
mm
mm

//2.3
//2.3
//2.3
//2.3
//2.3
//2.7

61.2°
46.4°
33.0°
22.2°
16.8°
11.2°

6
6

6
6
6

Gaussian type

cc cc
cc cc
cc cc

cc cc

Modified
Petzval

20
40
80

in.
in.
in.

//5.6
//14

3.4°
1.7°
0.85°

3
3
2

Table IV.

Wide-Angle

Lenses

for 16mm

Table II. Raptar Telephotos

Focal
length

//No.

Diagonal No. of
coverage elements

10 in.

//4.5

6.8°*

12 in.

//4.5

5.6°*

14 in.

//4.5

4.8°*

15 ;n.

//4.5

4.4°*

16 in.

//4.5

4.2°*

18 in.

//5.6

3.8°*

20 in.

//5.6

3.4°*

24 in.

//5.6

2.8°*

* Lenses marked with asterisk cover more
than the angle specified for 35mm single
frame with same high-quality performance.

Film

Focal
length

//No.

Diagonal No. of
coverage elements

3.7 mm

5.4 mm

12.7 mm

//I- 5
//1. 5
//1. 5

142°
84°
56°

Table V. Wide-Angle Lenses for 35mm
Film

Focal
length

//No.

Diagonal No. of
coverage elements

8.3 mm
11.2 mm

//1. 5
//2.0

142°
84°

targets used. Strict control of the
variables affecting the measurement is
very necessary. Other ways to evaluate
lens performance have been discussed
also.11"13 Since the subject is well
covered by these authors, no attempt
will be made to discuss any of the
methods as applied to the lenses which
are the subject of this paper other than
to state that the "Rayleigh-Conrady"
tolerances14 were used as the basis for
the comparison of these lens designs
with other similar designs, as well as
extensive photographic and optical bench
comparisons.

Spherical Mirror Optics (Mirrotels)

Since catadioptric photographic ob-
jectives are recent developments in the

field it is felt that some discussion of the
spherical mirror is necessary.

The advantages of the spherical
mirror as an image-forming device have
been known for many years. The
spherical aberration of a single concave
mirror is eight times smaller than that
of a single lens of equal aperture and
focal length even when the lens has the
most favorable bending for minimum
spherical aberration.2 Where high reso-
lution is desired, spherical aberration is
objectionable. Therefore, spherical mir-
rors have been made aspheric by hand
correction to minimize the spherical
aberration to acceptable limits. To
have the advantage of large-aperture
spherical mirrors with minimum
spherical aberration, Schmidt1 in 1930

Gilkeson and Turula: Optical Aids

499

added a corrector plate. Parabolic
mirrors with corrector plates have been
used. Only recently (Bouwers & Mak-
sutov2-3), however, has the spherical
aberration of the spherical mirror been
corrected by the addition of com-
mercially reproducible all-spherical cor-
rectors, thus making available the very
real advantages of reflective optics on a
wider scale than ever before. Perhaps
the most important and most obvious
advantage of the spherical mirror is the
complete absence of chromatic aberra-
tion. If a diaphragm is placed at the
center of curvature of a spherical mirror
no coma, astigmatism or distortion can
occur, for the straight line containing
the center of curvature parallel to any
given ray of light may be regarded as an
axis of the system. There is curvature
of field convex to the incident rays, the
radius of field curvature being about
equal to the focal length for objects at
infinity. Field curvature is rarely a
problem when the field of view is re-
stricted. Where field coverage relative
to focal length is large, suitable field
flatteners or curved film may be used.

An inconvenience of the spherical
mirror is the reversal in direction of the
light rays. There is some loss of light
since the object or image receiver inter-
cepts part of the useful beam. The
"shadow effect" can be serious with an
extensive field of view and small relative
aperture. The reversal in path, how-
ever, is a real and distinct advantage
for long focal length objectives because
the "folding" reduces total length to
about one-third that of a refractive
optical system of equal focal length,
thereby giving a more compact and
lighter system. Reflective optical sys-
tems require different mounting tech-
niques and are much more sensitive to
misalignment and spacing changes than
refractive optical systems. The correc-
tion of spherical aberration is achieved
by the addition of a weak spherical
corrector lens closely concentric with the
primary spherical mirror. With spheri-

cal aberration corrected, with coma,
astigmatism and distortion eliminated
by choice of stop position, and with
no chromatic aberrations present, the
resolution is primarily limited by dif-
fraction. The spherical mirrors are
mounted in a manner to eliminate focus
shift caused by temperature variations.
Such mounting is imperative by reason
of the very sensitive air space between
mirror surfaces.

Wide-Angle Lenses

The 84° and 142° wide-angle lenses
for 16mm film and 35mm film listed
in Tables IV and V have proven to be
invaluable where an extreme field of
view is required. The systems of the
lenses are basically reversed telephotos
in form. An extreme depth of field is
possible for the lenses even at the
maximum //1. 5 and //2.0 apertures
because of the very short focal lengths
and small residual aberrations with the
exception of distortion. The resultant
distortion is characteristic of extreme
wide-angle lenses of high relative aper-
ture. Successful application of the 142°
lenses in moderately high-speed motion
picture photography is discussed by
Bauer and Blake of the Douglas Aircraft
Go.15 The lenses are used to record
automatically instantaneous instrument
data shown on a wide variety of instru-
ments over a large area where the
distance from panel to camera is re-
stricted. In many cases the instrument
or objects must be located in azimuth
and elevation within the distorted
field, necessitating correction charts
to compensate for the distortion present
in the optical system. The charts are
made by photographing an accurately
drawn rectangular grid pattern at a
predetermined reduction with the lens
whose field is to be plotted. The grid
spacings are drawn, in both azimuth
and elevation, to subtend a given angle
in the field of the lens. The photograph
obtained is then enlarged with a dis-
tortion-corrected lens to a specified

500

December 1952 Journal of the SMPTE Vol. 59

size. The result is finally reproduced
in the form of graph paper for locating
and recording the data or objects.

The new 12.7 mm //1. 5 Cine Raptar
for 16mm cameras has been designed to
fill the need for a distortion-corrected
lens with minimum residual aberrations
where extreme coverage is not a primary
requirement. It has a diagonal coverage
of 56°.

In addition to the basic lenses and lens
mountings required, special attention has
been given to the varied needs of the
users. The most frequent requirements
are for compensation of focus shift
with temperature changes, and for
reticle reference-marking attachment.
Normal focus shift with temperature
changes may be accomplished by a
calibrated air-space change between
favorably disposed elements of the
system, or by spring-loading the elements
of the system against suitably placed
invar rods. The method used is de-
termined by the lens design. The
correction of focus shift with temperature
is most necessary for long focal length
lenses.

Many applications of high-speed mo-
tion picture photography in the field
require a reference mark within the
picture area. This is accomplished
with an optical reference-marking at-
tachment whose residual aberration
contributions to the primary lens must
be kept at a minimum. The optical
reference-marking attachment is com-
posed of a cross-line engraved field lens
and a high-aperture lens which images
the cross lines and the image due to the
primary objective on the film at 1:1
ratio.

This attachment is par-focussed and
can be used with any of the high-speed
motion picture camera lenses, and can
be adapted easily to other applications.

A means for focussing the lenses is
often required and provision is made
for focussing the majority of the lenses
wherever it is required. There is also

some demand for viewing devices
through which it is possible to follow
the action being photographed. Where
required, such devices can be manu-
factured and supplied. Every attempt
has been made to supply to the user in
the field a wide variety of lenses, devices
and aids to simplify and expedite his
work, which is so essential in the common
defense effort today.

References

1. B. Schmidt, "Ein Lichtstarkes Koma
Freies spiegel system," Mitteilungen
Hamburger Sternwarte in Bergedorf (Re-
ports of the Hamburg Observatory in
Bergedorf}, 7: 15-17, 36, 1932.

2. A. Bouwers, Achievements in Optics,
Elsevier Press, 402 Lovett Blvd.,
Houston 6, Tex., 1946.

3. D. D. Maksutov, "New catadioptric
meniscus systems," J. Opt. Soc. Am.,
34: 270-284, May 1944.

4. K. Pestrecov, "Resolving power of
photographic lenses," PSA Jour., 13:
155-158, Mar. 1947.

5. K. Pestrecov, "Resolving power of
photographic lenses," Photogrammetric
Eng., 13: 64-85, Mar. 1947.

6. F. H. Perrin and H. C. Hoadley,
"Photographic sharpness and resolving
power," J. Opt. Soc. Am., 38: 1040-
1053, Dec. 1948.

7. Paul L. Pryor, "Air Materiel Com-
mand research on resolution and
distortion," Photogrammetric Eng., 12:
89, Dec. 1946.

8. C. W. Kendall and B. A. Schumacher,
"Measuring the resolving power" of
lenses," Photo Tech., 3: 51, Apr. 1941.

9. L. E. Jewell, "A chart method of testing
photographic lenses," J. Opt. Soc. Am.,
2-3: Nos. 3-6, 51-61, May-Nov. 1919.

10. L. E. Hewlett, "Photographic resolving
power," Can. J. Research, Sec. A, 24:
15-40, Apr. 1946.

11. M. Herzberger, "Light distribution in
the optical image," J. Opt. Soc. Am.,
37: 485-493, June 1947.

12. O. H. Schade, "Electro-optical charac-
teristics of television systems: Intro-
duction," RCA Rev., 9: 5-37, Mar.
1948.

Gilkeson and Turula: Optical Aids

501

"Part I — Characteristics of vision and
visual systems," ibid., 13-37, Mar.
1948.

"Part II — Electro-optical specifica-
tions for television systems," ibid.,
245-286, June 1948.
"Part III — Electro-optical charac-
teristics of camera systems," ibid., 490-
530, Sept. 1948.

"Part IV — Correlation and evalua-
tion of electro-optical characteristics
of imaging systems," ibid., 653-686,
Dec. 1948.

13. A. Marechal, "Etude des effects
combines de la diffraction et des

aberrations geometriques sur 1'image

d'un point lumineux,"

Part I — Rev. optique, 26 and 27: 257-

277, Sept. 1947.

Part II — ibid., 74-92, Feb. 1948.

Part III — ibid., 270-287, May 1948.

14. A. E. Conrady, Applied Optics and
Optical Design, Oxford University Press,
London, 1929, pp. 137, 393, 433.

15. Harold E. Bauer and Webster Blake,
"The applications of wide-angle optics
to moderately high-speed motion pic-
ture cameras," presented on Oct. 9 at
the Society's 72d Semiannual Con-
vention at Washington, D.C., and
planned for early publication in the
Journal.

502

December 1952 Journal of the SMPTE Vol. 59

A High-Speed Rotating-Mirror
Frame Camera

By BERLYN BRIXNER

A high-speed framing camera of some general utility has been developed
at the Los Alamos Scientific laboratory and operated up to 3,500,000 frames/sec.
Use is made of a rotating mirror and 170 framing lenses working at f/26 to
produce frame pictures 1.2 X 1.4 cm in size. Another model operating at
100,000 frames/sec has been made with 90 circular frames 2 cm in size.

JL HE CONTINUOUS-WRITING high-speed
frame camera herein described was made
for the detailed study of explosive
phenomena and is primarily useful for
the photography of high-speed events
that are self-luminous or illuminated by
very intense explosive light sources
using an argon atmosphere.1 Frame
cameras operating up to 500,000 frames/
sec have been made,2*3 but the systems
used probably cannot he increased in
speed to any great extent because of the
limitations of the strength of the rotating
mirrors used. The camera to be de-
scribed was designed for operation up to
3,400,000 frames/sec and makes use of
a small mirror so that much higher
rotational speeds can be obtained.

Optical System

The principle of operation of the
camera is the same as has been used in

Presented on October 9, 1952, at the So-
ciety's Convention at Washington, D.C.,
by W. E. Buck for the author, Berlyn
Brixner, University of California Los
Alamos Scientific Laboratory, P.O. Box
1663, Los Alamos, N.M.

highest-speed cameras previously made
in that an object to be photographed is
imaged on the surface of a rotating
mirror and then relayed to successive
positions on the film by a series of relay
lenses. The novel feature of this camera
is the use of a small, thin, two-faced
rotating mirror and the division of the
optical system into two sections so that
appreciable blind time is avoided.

Figure 1 shows a schematic isometric
view of the optical system. The ob-
jective lens LI forms an image Ii in
the field lens L2. The beam-splitting
mirror MI divides the light from Ii into
two paths A and B. Consider path A
first. The combined relay and field
lens L3A relays the first image Ii to the
position I2A near the surface of the
rotating mirror RM, using the mirrors
MZA and M3A to properly direct the
light path. The mirror M3A is so placed
that the rays forming the image I2A are
reflected from the surface of the rotating
mirror RM into the final relay lens L4A
to form the image ISA in the film plane
FA. A series of lenses identical to L4A
are placed in the 1 80° arc shown to form

December 1952 Journal of the SMPTE Vol. 59

503

Fig. 1. Optical diagram of high-speed frame camera.

a series of pictures on the film FA. This
lens and film arc records pictures for
the rotating mirror in the range of
±45° from the position shown. For
positions of the rotating mirror beyond
that range it is necessary to follow the
optical path B which is seen to be at
90° around the Z axis from path A.
The combined field and relay lens L3B
then relays the image Ii to the position
I2B- The image-forming rays are so
directed that they pass into the relay
lens L4B to form the image I SB in the
film plane FB. It is thus seen that
pictures are obtained for another 90°
range of the rotating mirror, adjacent
to the previous 90° range, or a total of
180°. Since both faces of the rotating
mirror are polished, pictures can be

obtained for the entire 360°, with the
exception of the region obscured by the
mirrors M3A and MSB which amounts to
less than 3% of the cycle in a practical
case. There are always two images
on the rotating-mirror face but the
displacement of the relay lens arcs
away from the X-Y plane insures that
light from only one reaches a relay lens
at any one time. Achromatic doublet
lenses are used throughout since these
give excellent resolution over the small
angular field required. The axes of
the final relay lenses are coincident with
the central optical path and hence the
film plane is a conic rather than a
cylindric section as shown. The various
lenses of the system are assigned focal
lengths such that the pupils are located

504

December 1952 Journal of the SMPTE Vol. 59

Fig. 2. Exterior view of high-speed frame camera.
Berlyn Brixner: Rotating-Mirror Camera

505

Fig. 3. High-speed shutter used with frame camera.

at the objective lens, the beam splitter,
and the final relay lenses. This insures
even illumination for all the points of
the final image and the minimum ex-
posure time for each picture. To obtain
a rate of 3,400,000 frames/sec, a series
of 85 framing lenses were used for each
of the 180° arcs and the rotating mirror
operated at 10,000 rps (revolutions per
second).

The loss of light entailed by the use of
a beam-splitting mirror may be objec-
tionable to some users even though a
factor of 2 or 3 in exposure usually
makes only a minor change in the final
print quality. In that case the use of
a roof mirror in place of the partial
reflecting mirror is advisable. The use
of a roof mirror also introduces the need
for the objective lens to be of twice the
aperture and may result in appreciable
distortion in the final image. The
objective lens axis is then placed midway
between the A and B optical paths.

The shutter for the camera is located
between the field lens L.2 and the beam
splitter, since this part of the system has
a small aperture. The shutter must be
closed within 1/20,000 sec after the start
of exposure or recycling and multiple
exposure will occur. Since a me-
chanical shutter cannot operate in such

a short time it was necessary to devise
a much faster mechanism. A small
block of glass can be rendered suffi-
ciently opaque within a few micro-
seconds by shattering it with a shock
wave from a high-explosive detonator.
Such an arrangement has been found
practical if the glass is enclosed in a
suitable steel case.

Camera Construction

The exterior of the camera is shown in
Fig. 2. The tube at the top is the
focusing mount for the 24-in. objective
lens used. The electrical controls for
operation of the camera are mounted on
the circular end plate. The rectangular
projection on the plate is the high-
speed explosive shutter mentioned above.
It is easily removed for loading with a
glass block and the explosive detonator.
The viewfinder is located just above the
shutter. The adjustable time-delay and
detonator firing circuits are housed
within the camera body. The two semi-
circular relay lens rings and film holders
are seen at the rear of the camera.
Standard 35mm camera cassettes are
used to hold the film.

The disassembled explosive shutter is
shown in Fig. 3. It is made of steel
and withstands the detonator explosion

506

December 1952 Journal of the SMPTE Vol. 59

Fig. 4. 10,000-rps turbine with rotating mirror.

without any noticeable deformation of
the piece. The ^-in. round optical
aperture is near the center of the
shutter. Circular pieces of transparent
plastic are fitted in these holes to prevent
glass fragments from entering the camera.
The block of ^-in. plate glass fits in the
long groove. The electric detonator
(not shown) is pressed against the end
of the glass block by means of the hollow
screw which fits in the shutter cap. A
chamber is formed around the detonator
so that the explosive gas pressure will
not be too high before exhausting to
the outside through the ports in the cap.
The detonator is loaded after the shutter
has been assembled and fitted to the
camera.

The 10,000-rps rotating mirror and
air turbine drive4 is shown in Fig. 4.
The mirror has faces 1 5^ X 1 1^ mm and
is 8 mm thick. The air and oil lines
for driving and lubricating the unit are
at the left. The compact construction
was achieved by combining the mirror
and turbine into a unit. There is a
turbine and sleeve' bearing at each end
of the mirror. Dural bucket wheels
are press-fitted on the mirror shaft.
Ordinary No. 10 grade lubricating oil
at 100 psi in a circulating system is
used for lubricating and cooling of the
bearings. The bucket-wheel manifolds
are so arranged that the exhaust air

sweeps the bearing-oil leakage out the
exhaust pipe so that it will not deposit
on the mirror and optics inside the
camera. A 19 X 17 J mm drive has
also been constructed so that image
cutoff is avoided when the mirror is at
45° to the optic axis. This larger size
mirror operates with very little strength
safety factor at 10,000 rps, and its use
is avoided when the highest speed of
operation is required.

The camera has an effective aperture
of f/26 and the final image size is
12 X 14 mm. Dynamic resolution tests
with Shell Burst Panchromatic film
give 30 lines/mm over the entire picture
area. Diamond shaped stops5 are used
for the lenses as it has been found that
there is no practical loss of resolution
relative to a circular or rectangular
stop of the same linear dimensions. The
diamond stop has the advantage that
the effective time of exposure is about
two-thirds of that obtained by a rec-
tangular stop.

The design of the camera is such that
it is adaptable for a wide range of operat-
ing speeds. Another model almost iden-
tical in appearance to the one illustrated
was made for operation at 100,000
frames/sec to give 90 20-mm diameter
images. It uses an electric motor drive
to give a mirror speed of 550 rps.

Berlyn Brixner: Rotating-Mirror Camera

507

Fig. 5. Photograph of the surface of an explosive-driven metal plate.

Sample Photographs

The photographs in Fig. 5 are a few
of the frames from a series showing the
surface of an explosive-driven metal
plate6 by reflected light. An explosive
flash with an argon atmosphere was used
to illuminate the plate and the camera
was operating at about 3,500,000 frames/
sec. The first frame shows the surface
of the plate just before it was struck by
a shock from behind. The dark lines
are from the reticle in the optical system
of the camera. The fine triple-line
reticle is painted on the plate. The

second frame shows the plate within
0.3 /isec after being struck by the shock.
There is a considerable increase in the
contrast of the reticle lines and trivial
imperfections of the plate surface show
up strongly. A velocity of 3,000 m/sec
is attained almost immediately and the
movement is easily ' detected on the
succeeding frames by examination of the
relative positions of the two reticles.

Figure 6 shows a contact print of the
sequence of negatives obtained when
exploding primacord was photographed
in silhouette at 1,700,000 frames/sec.
A scale has been placed adjacent to the

508

December 1952 Journal of the SMPTE Vol. 59

ft ft V U 4>

• ft ft v 4* u

> iff U U

ft W 4> O

t» W 4> 0

» ft M 4> W

ft ft « tf U 4>

ft ft M M 4> w

• 41 I* «f 4> 4>

O ft N O 4> i>

ft ft M O 4> U

Fig. 6. Contact prints of film showing exploding primacord.

primacord to facilitate measurement, and
an explosive light source was used. The
early frames show the light source as it
brightens up, and shortly thereafter the
shock wave from the primacord can be
seen to progress across the illuminated
area. The shock wave was found to be
traveling at 6.2 mm//,isec along the
primacord.

Figure 7 shows a 10 X enlargement of
one of the frames from Fig. 6.

Conclusion

The continuous-writing frame camera
described is the fastest practical camera
so far produced. Its use is probably
largely limited to the study of high-
explosive phenomena where the destruc-

Berlyn Brixner: Rotating-Mirror Camera

509

Fig. 7. 10X enlargement of photograph showing exploding primacord.

tion of the object being examined is of
no importance. Somewhat slower
models of the camera (with even better
space resolution) can undoubtedly be
used to obtain reflected light photo-
graphs of objects illuminated by the high-
intensity gas-discharge lamps. The
camera is rugged in construction and
can be readily moved about. It has
been found that the sequence of 50 to
100 frames obtained is quite adequate
for the studies so far encountered.

References and Notes

1. W. D. Chesterman, The Photographic
Study of Rapid Events, Clarendon Press,
Oxford, England, 1951, p. 54.

2. C. D. Miller, "Half-million stationary
images per second with refocused

revolving beams," Jour. SMPE, 43:
479, Nov. 1949.

3. J. S. Stanton and M. D. Blatt, "Bowen
76-lens camera," NAVORD Report
1033, 1948.

4. The perfection of this rotating mirror
drive is largely due to the efforts of
W. E. Buck, Los Alamos Scientific
Laboratory of the University of Cali-
fornia, Los Alamos, N.M., with con-
siderable assistance by Prof. J. W.
Beams, University of Virginia, during
the initial development stage.

5. The use of diamond stops was suggested
by T. E. Holland, Los Alamos Scientific
Laboratory of the University of Cali-
fornia, Los Alamos, N.M.

6. W. E. Deal and R. G. Shreffler, "Free
surface properties of explosive driven
metal plates," Phys. Soc., Salt Lake
City, Utah, June 27, 1952.

510

December 1952 Journal of the SMPTE Vol. 59

Discussion

Dave Miller (Chairman of the Session;
Battelle Memorial Inst.} : I would like to
congratulate the author, Berlyn Brixner,
on making some progress toward a name
for this camera, which it needs rather
badly. It has often been called the
"Rotating-Mirror Camera." There is a
good deal of ambiguity there because the
term "Rotating-Mirror Camera" might
apply to a camera which simply causes
an image to move continuously on a film
and might not necessarily refer to this
type of camera in which a reflected beam
of light rotates about a focused image as
a center. I have invented my own name
for this type of camera which I shall
describe at the next session of this sym-
posium.

Jean St. Thomas (Civil Aeronautics Admin.) :
How do you eliminate schlieren patterns
of the air surrounding the mirror, or does
the mirror run in a vacuum?

[Mr. Buck, who read the paper, replied. The
following more tightly knit answer has been
supplied by the author.] Schlieren patterns
in air are made visible by means of colli-
mated light beams or an equivalent system
using a point light source and a restricting
field stop in a suitable optical system. The
image on the camera's rotating mirror is
formed by //32 beams and these are
sufficiently large so that no schlieren pat-

terns are visible. The optical disturbances
in the air surrounding the mirror could
easily deteriorate the final image resolution
were it not for the fact that they occur
adjacent to the image on the mirror and
hence have only a short optical lever arm
with which to operate. If there were
trouble of this kind, it could be greatly
reduced by using some gas with a high
sound velocity for the mirror atmosphere,
for example helium or hydrogen. The
latter is dangerous to use because of its
highly inflammable and explosive nature.

Mr. Miller: I can't recommend rotation
in a vacuum as a solution to the problem of
these high-speed rotating mirrors. That
caused us no end of grief at NAG A;
because of the absence of air, oil spattered
without limit and the very negligible
amount of oil that came through the
bearing came up onto the rotor and
spattered off onto the optics. It presented
a problem without any solution. We tried
for months every conceivable sort of trap
to eliminate this spattered oil, but we were
not successful. And because of that fact
we had to resort to an electromagnetic
suspension and an electromagnetic drive
for the rotor, as long as we spun it in the
vacuum. With the electromagnetic drive
I understand this rotor, weighing two-
thirds of a pound, eventually reached a
speed of 4,000 rps, corresponding to
800,000 frames a second for that camera.

Berlyn Brixner: Rotating-Mirror Camera

511

Acoustic Problems at the "Waldbuhne:
Open-Air Sound Theater in Berlin

By HANS SIMON

Acoustic problems arising in connection with the reproduction of sound films
in an open-air theater are discussed. The proper arrangement of loud-
speakers as well as the careful adjustment of their beam direction is of utmost
importance. It is demonstrated that a uniform sound level with a consider-
able increase in volume can thereby be attained. Furthermore, as a result
of the concentration of sound waves, a substantial increase in the frequency
band will occur. The amplifier power necessary for the required acoustic
output is calculated.

JL HE OPEN-AIR theater known as
Waldbiihne Berlin, built about twenty-
five years ago, has now been arranged
for the reproduction of sound films.
Figure 1 shows the screen with the loud-
speaker installations mounted on both
sides. The front row of seats is about
164 ft and the back row 394 ft from the
screen. For these viewing distances a
36 X 26 ft screen was used. Repro-
duction of sound films had to be satis-
factory for the entire audience of 25,000
persons. To meet this requirement it
was essential to achieve adequate syn-
chronization of picture and sound and
uniform sound level in all parts of the
arena.

Synchronization

It is obvious that acoustic quality in
an open-air theater is dependent on very

A contribution submitted on September
23, 1952, by Hans Simon, 6 Xantener
Str., Berlin W. 15, Germany.

different conditions from those in a
closed room. In an open-air theater
all the effects due to reverberation are
absent and only the laws for linear and
unrestricted diffusion of sound waves
need be considered. Their velocity of
diffusion, however, will be of particular
importance. The long distances sound
must travel in an open-air theater tend
to produce an undesirable effect on the
audience due to the time-lag between
picture and sound. Consequently, scenes
of rhythmic movement such as a dance
would deviate from the rhythm of the
accompanying music. Similarly, it
would be especially disturbing if the
sound produced by a singer were not
synchronized with lip movements. It
is therefore of the first importance that
the phase difference between picture
and sound be reduced to a minimum.
The solution which proved successful
for the Waldbiihne Berlin is described
as follows.

As far as is now known, the following

512

December 1952 Journal of the SMPTE Vol. 59

Fig. 1. The Waldbiihne Berlin Open-Air Sound Theater

method is the only one that can be used
satisfactorily to reproduce sound films
for large audiences. The method used
takes advantage of the ability of human
eyes and ears to perceive optical and
acoustic phenomena belonging together
as synchronous when the time-lag be-
tween them is not too great. According
to experience the time-lag must not
exceed 0.1 sec*; whether the picture
or the sound precedes is unimportant.
Therefore, if at A (Fig. 2) there is perfect
synchronization, then virtual synchroniza-
tion will occur for all viewers seated
within a range of 112 ft (i.e. 0.1 sec)
each side of A. Hence the radius of
virtual synchronization is 224 ft. Since
the value of 0.1 sec may not be exceeded
for the reasons stated above, the syn-
chronization area of 224 ft must be taken
as the limit beyond which no satisfactory

* The normal limit used in synchronization
practice.

reproduction of sound films is possible.
Therefore, the use of an open-air theater
for sound will always be limited to a linear
distance of 1 72 ft either side of the calculated
line of synchronization. Satisfactory vision
in this area is dependent solely on the
size and illumination of the screen and,
therefore, on the light output of the
projector.

The vertical section of Waldbiihne
Berlin (Fig. 2) shows that the distance
of A from the screen corresponds to 0.25
sec (sound path = 276 ft). To obtain
synchronization at A the sound produced
by the loudspeaker must precede the
picture by 0.25 sec. This may be ac-
complished by using a special copy of
the film or by altering the length of the
film loop between the film gate and the
sound head of the projector. Since this
is a problem of construction it will not
be discussed further.

In actual practice, this method of
preceding picture by sound produced

Hans Simon: Open-Air Sound Theater

513

Screen

Figure 2.

Screen

acceptable synchronization throughout
the 224-ft area.

Uniform Sound Level

Uniform sound level for all parts of
the arena was obtained by appropriate
distribution of the loudspeaker units
and by carefully adjusting their beam
direction. Each of the loudspeaker
units consisted of two groups of three
speakers of different frequency charac-
teristics. Numerous tests showed that
the most suitable arrangement was

obtained with the loudspeaker units
placed on both sides of the screen (Fig. 1)
at about two-thirds of its height.* A
great many tests and measurements were
necessary to obtain the correct adjust-
ment of the sound direction for all the
loudspeaker units. The final result of
the measurement of the sound levels
may be seen in Fig. 3. With an average

* This distance was determined by the
structure of the Waldb"hne Berlin and
must not be assumed to be generally
acceptable.

514

December 1952 Journal of the SMPTE Vol. 59

S 88

00 O

Frequency in Cycles per Second
Figure 4.

sound level of 77 phonsf the deviations
were nowhere more than 3 phons. The
final arrangement of the loudspeaker
units and their adjustment resulted in a
considerable improvement of the sound
level through the frequency range.
This result, based on theoretical cal-
culation, is produced by the effect of
concentration due to the adjustment of
the loudspeaker units.

A comparison of the loudspeaker ar-
rangement described above with that
of an arrangement located at one-
quarter of the screen height without
special adjustment of the loudspeaker
direction may be of interest. Figure 4
shows the frequency characteristics taken
at a distance of 262 ft from the loud-
speaker units. Curve II refers to the
loudspeaker arrangement at one-quarter
the screen height while Curve I refers
to the final arrangement. The data for
both curves were obtained with the
loudspeakers equally powered (50 v),
corresponding to an amplification power

of about 40 w. Comparison of the two
curves shows an increase in the sound
level of about 8 phons within the range
of 100-8000 cycles/sec. Concentration
of the sound waves produced consider-
able improvement in acoustic efficiency
and eliminated overloading at high
sound levels, i.e. distortion.

In addition, it is evident from the two
curves that a notable enlargement of
the frequency band in both high and
low ranges has occurred. If Ji and Jn
be the amount of energy of sound at
loudspeaker units I and II, the following
equations apply:

101ogJr; -a

10 log ^ = a + 8
Jo

where Jo is the sound energy at threshold.
Subtracting the first equation from the*
second :

f The loudness level, in phons, of a sound
is numerically equal to the sound pressure
level in decibels, relative to 0.0002 micro-
bar, of a simple tone of frequency 1000
cycles /sec which is judged by the listeners
to be equivalent in loudness.

10 log ^ - 10 log i-

Jo J0

or 10 log ^

Jjl
Ji

8
8

.8
6.3

Hans Simon: Open-Air Sound Theater

515

These sound measurements were made
using continuous tones. The signifi-
cance of such an increase in the sound
level (8 phons) becomes apparent when
it is realized that this corresponds to
an actual power ratio of 6.3 times. In
other words, proper orientation and
placement of the speakers resulted in an
improvement in acoustic efficiency by a
factor of 6.3.

Amplifier Power

Finally, the amplifier installed at the
Waldbiihne Berlin may be described.
It was considered desirable to create
a sound level of 70-75 phons at the back

of the theater. Since it is known that
with each 325 ft of sound path loss of
sound energy is 5-7 phons, the acoustic
power required was calculated to be
8-10 acoustic w. To produce this with
the loudspeakers used called for an
amplifier power of about 120 electrical
w. A potential 1 50-w unit was installed
to satisfy special conditions such as the
attenuation of sound waves occurring
with changes of temperature.

According to the judgment of experts
the technical problems arising from the
use of the Waldbiihne Berlin as an
open-air theater for sound reproduction
have been solved quite satisfactorily.

Errata

Raymond Spottiswoode, N. L. Spottiswoode and Charles Smith, "Basic principles of
the three-dimensional film," Jour. SMPTE, 59: 249-286, Oct. 1952.

Page 254, column 2, footnote, last line:
For: 1 metric p = 10,000/distance in cm.
read: Distance in metric p = 10, 000 /distance in cm.

Page 256 : Fig. 2b title, next to last line :
For: When tc > te, I — r' > I - r
read: When // > tci I - r' > I - r

Page 271, column 2: The equation numbered 11 should be numbered 18.

516

December 1952 Journal of the SMPTE Vol. 59

Some Geometrical Conditions

for Depth Effect in Motion Pictures

By EUGENE MILLET

The fundamental considerations affecting stereoscopic vision are used as
a basis of a description of the Kern-Paillard Bolex stereo system for 16mm film.

JL HE PERCEPTION of a stereoscopic
image is a complex phenomenon;
the process of synthesis whereby one
forms an accurate idea of an object
observed in all its dimensions from the
elementary data of the senses involves
both psychology and cerebral physiology.

It is obvious that, for purposes of arti-
ficially producing the impression of depth
by means of plane images, only the
sensory aspect of the problem need be
considered; the illusion would be com-
plete if all the sensations present upon
observation of the object in nature could
be produced artificially at the same in-
tensity as in natural vision.

The purely optical sensations due to
the two retinal images depend on con-
ditions of definition, accommodation,
coloration, distribution of light and
shade, perspective, and movement of the
object. In addition, the state of con-
vergence of the eyes produces certain
muscular sensations which play an im-
portant part in effortless depth vision.

A contribution submitted October 14,
1952, by Eugene Millet, Development
Dept., Paillard S.A., Yverdon, Switzer-
land; and Paillard Products, Inc., 265
Madison Ave., New York 16, N.Y.

When an object located at a finite
distance in nature is observed with the
naked eye, the axes of the two eyes con-
verge upon a certain point on the object,
and its various elements are seen at un-
like angles by the left eye and the right.
In a stereoscopic cinematographic pro-
jection, the spectator views two images
on a screen, whose dimensions are gen-
erally different from those of the object
originally photographed; moreover, the
angle at which each eye sees the object
depends on certain of the technical con-
ditions under which the shot was taken.
We shall inquire, by a simple geometrical
approach, what conditions must be satis-
fied in order that the spectator will see
the projected image at the same angles
at which he might have seen the object
in nature.

Conditions for Natural Relief

We define "natural relief" in the
following way:

Let there be an object A occupying a
certain space in nature. Having photo-
graphed this object, we view a pair of
images A' on a projection screen. We
speak of natural relief if all the dimensions
of A ' are seen by each of the spectator's
eyes at angles equal to those at which

December 1952 Journal of the SMPTE Vol. 59

517

Fig. 1. Relationship between transverse and axial enlargement.

each eye respectively would see all the
dimensions of A in nature when stationed
at the desired distance from A.

First let us recall, the relationship sub-
sisting between transverse enlargement
and axial enlargement in direct vision of
an object in nature (Fig. 1).

Let Ox be the ocular axis, and let h
be a transverse object element and a an
object element along Ox. The elements
h and a are assumed small relative to the
distance D. Designating the ocular base
by 2b0, we have

ft = h/D;
ab0/D(D - a).

(D
(2)

If the observer stations himself at a
point O, we have

0 = h/D; (T)

a = ab0/D(D - a}. (2)

Upon displacement of the observer
from 0 to 0, h undergoes an apparent
transverse percentage enlargement of

Et = p/p = D/D,

(3)

and a an apparent axial percentage en-
largement of

Ea = a/a = D(D - a}/D(D - a}. (4)

Replacing D in (4) by its value from (3),
we have

(5)

L) I tLi — a

The viewing of an object in nature is

thus subject to two simple rules (3) and
(5).

To the naked eye, the only way to
vary the apparent dimensions of an
object is to approach it or withdraw from
it ; if, in the course of such a relocation
of the observer, the angles at which he
sees the transverse dimensions of the
object have varied in a proportion Eh
the angles at which he sees an axial
element a will have varied in a propor-
tion Ea dependent upon Et by the
relation (5).

To determine what conditions must
be met by a stereoscopic projection in
order for the spectator to see any image
whatsoever in natural relief (in the sense
of our definition), we shall proceed as
follows :

A spectator stationed at a distance
D' from the projection screen sees a
transverse element h" of the image A ' at
an angle ft'. We first inquire at what
distance D from the object A one would
have to be stationed in nature in order
to see the transverse element h at an
angle p = &'. From this distance D,
we should see the axial element a at an
angle a, and we must find under what
conditions the spectator at distance D'
from the screen will see the image of a
at an angle a ' — a. The latter equality
must hold regardless of the value of a.

Let a photographic lens of focal length
fv be placed at a distance Xv from the
object photographed; on the film, it
projects an image h' of h such that

518

December 1952 Journal of the SMPTE Vol. 59

Figure 2.

h' = hfv/Xv.

(6)

If a projection lens of focal length fp
projects this image A' on a screen placed
at a distance Xp, the image h" on the
screen will have the dimension

h" = h'Xp/fp = hfvXp/fpXv. (7)

A spectator stationed at a distance Dr
from the screen sees h" at an angle ft'

ft > = h "/D = hfvXp/fpXv -\/D'. (8)

The distance D at which one must be
stationed to see h at the angle j8 = 0' in
nature is given by

h/D = hfvXp/fpXv- \/D',
or D=fpXv/fvXp-D'. (9)

Consider a shot of the axial element a
with a semibase bv (Fig. 2).

* = afvbv/Xv(Xv - a}. (10)

Upon projection, we obtain an image
k ' of k on the screen :

k' = kXp/fp,
hence k' = afvbv/Xv(Xv - a)-Xp/fp. (11)

The spectator sees k' at an angle a'

(12)
We are to have a.' = a, or

fvXp/fpXv-\/D'.abv/(X, -a)-

ab0/D(D - a). (13)

The value of D is given by (9). Intro-
ducing this value of D into (13), we
have

The condition (14) must be satisfied for
any value of a whatsoever, and the ratio
b0/bv cannot vary with a. It is therefore
necessary that ()(6«/69)/(ta = 0 no mat-
ter what a is, or that

Xv = D'fpXv/fvXp = O. (15)

This relation (15) determines the value
of/)7

D' = Xpfv/fp. (16)

Substituting this value of D' in (14),

b0/bv = 1, 60 = 6,; (17)

in (9), D = Xv; (18)

in (8), 0' = A/*.; (19)

and in (12) a' - abv/Xv(Xv - a). (20)

To summarize, the spectator receives the
illusion of natural relief if the following
two conditions are satisfied:

1. The camera base must be equal to
the ocular base (relation 17);

2. The spectator must be stationed
along the axis of projection at a distance
from the screen which is to the projector-
screen distance as the focal length of the
camera lens is to the focal length of the
projection lens (relation 16).

Relations (18), (19) and (20) show us
that when conditions 1 and 2 above are
satisfied, the spectator will see all the
dimensions of the image at the same
angles as the photographer saw the corre-
sponding dimensions of the object while
shooting.

Condition 1 is readily satisfied by
construction; the camera must have a
base between 63 and 67mm.

As for condition 2, it is to be noted

Eugene Millet: Depth Effect in Motion Pictures

519

Fig. 3. Convergence and stereoscopic depth of field.

that this condition cannot be satisfied
strictly for any spectator; for it is im-
possible to have the spectator's head on
the axis of projection without casting a
shadow on the screen. Still, it must be
remembered that the closer the spectator
is to the axis, the more closely the ob-
served depth effect will approach natural
relief. Again, if the spectator is not
stationed at the distance D' from the
screen as defined by (16), he will see a
somewhat distorted relief. In particular,
if the spectator is farther from the screen
the image of an axial element a, or the
segment transversely projected into k',
will suffer an apparent enlargement Eaf
equal to the apparent enlargement Et'
suffered by the image h" of h. Upon
projection, therefore, we have Ea' =
Etf — 1. In nature, if the observer had
withdrawn from the object so that the
transverse dimensions would suffer an
enlargement Et = Etr, the axial ele-
ment would have suffered an apparent
enlargement.

= Et'

D -

D/Et' - a

given by (5).

Ea/Ea' =

Comparing Ea and Ea ',
D - a

DlEt' - a

Having assumed
D/Et' - D and

Et' — 1,

have

- Ea.

We can therefore conclude that if the
spectator is farther from the screen, the
depth of objects will be exaggerated,

while if he is closer to the screen, the
picture flattens.

The choice of focal lengths of cameras
and projectors must be such that the
largest possible number of spectators can
be placed near the position of natural
relief; this position should not be too
close to the screen, since the spectators
at optimum distance would then neces-
sarily be fairly far away from the pro-
jector-screen axis.

Stereoscopic Depth of Field

Comfortable stereoscopic vision is im-
possible unless the extreme frontal planes
of the object lie within two definite
limits.

Let A\ and A2 be the intersections of
the two extreme frontal planes of the
object with the ocular axis of the eyes 0,
semibase b0. The convergence is 71 =
2b0/Dl at Ai and y2 = 2b0/D2 at A2
(Fig. 3). For comfortable observation
of the object, it is necessary that the
maximum increment of convergence of
visual rays, i.e. the difference 71 — 72,
should not exceed a certain limiting
value. This limiting value, unfortu-
nately, varies from one observer to an-
other; some people find a convergence
differential of as little as 1° slightly
troublesome, while others tolerate much
higher differentials without fatigue.
Since a stereoscopic film is to be viewed
by numerous spectators, we must adopt
a maximum value of 71 — 72 sufficiently
small so that anyone may witness the
performance without fatigue. At the
same time, the limit must not be too

520

December 1952 Journal of the SMPTE Vol. 59

Of in meters

70
in mefew

Fig. 4. Corresponding values of DI and Z)2 for determining stereo depth of field.

low, so that photographic possibilities
will not be excessively restricted. As
the maximum convergence differential,
we therefore take 71 — 72 = 70'; this
value, which seems reasonable for prac-
tical purposes, is in accordance with the
stereoscopic projection German Stand-
ard DIN 4531 (July 1949, Beuth-Vertrieb
GmbH, Berlin W15 and Koln).

In the case of cinematographic equip-
ment, when the camera base is equal to
the ocular base, the convergence differ-
ential is the same for the spectator view-
ing the image a' at a distance Dr =
Xpfv/fp from the screen and for the
photographer viewing a in nature while
shooting.

We may therefore say that D\ and Z)2
are the distances from the camera to the
boundaries A\ and At of the subject,
within which the photographer can shoot
without exceeding a visual convergence
of 71 — 72 for the spectator at distance
D ' from the screen.

We have

71 -72 -2b0(\/D, - 1/JD,),

l/£i -

(21)

If 7i - 72 = 70' = 0.02 radians and
2b0 = 64mm,

we have l/Dj - 1/Z>2 = 0.3125 (2~T)

when DI and Z)2 are expressed in meters
(Fig. 4).

For example, if we are to photograph
a subject whose most distant part is at

DZ = 5 m from the camera, the relation
(21) shows us that no part of the scene
photographed should then be less than
D\ — 1.95 m from the camera.

This limit on convergence differential
therefore determines a maximum picture
depth as a function of the range — a
depth of field, called the stereoscopic
depth of field.

Stereoscopic Depth of Field and
Position of Projector Windows

In a stereoscopic projection, the field
of the image projected is bounded
laterally and vertically by the projector
windows. The two projector windows
form a stereoscopic pair, and depending
on the lateral position of the windows
with respect to the centers of the images
photographed, the resultant image will
be more or less distant from the spectator.
For example, if the windows were cen-
tered with respect to the images of the
points at infinity^ along the axes of the
camera lenses, the picture would seem
to be located at infinity; with such a
set-up we would always have D2 = oo,
and no object could be photographed at
less than DI = 3.2 m from the camera,
otherwise the picture image would pro-
ject beyond the stereoscopic depth of
field.

Thus it turns out to be desirable to
make the set-up such that the stereoscopic
image of the projection windows seems
to be an object located at 3.2 m from
the camera. The frame then looks like

Eugene Millet: Depth Effect in Motion Pictures

521

Fig. 5. Schematic diagram showing
the path of rays through both openings
at 64 mm, through prisms to the Yvar
lenses, then on to 16mm film.

a window through which the spectator
sees everything that has been photo-
graphed between 3.2 m and infinity.

Objects closer to the camera than this
may be photographed. If the most dis-
tant plane of the subject is 3.2 m from
the camera (Z>2 = 3.2), objects as close
as 1.6 m (Z>i = 1.6) may be filmed. The
image will then seem to be between the
window and the spectator, and pre-
cautions should be taken while photo-
graphing so that features situated in front
of the window will not seem to be cut
off by its edges.

In order to photograph at distances
of less than 1.6 m, it would be necessary
to change the position of the frame in
order for the entire view to lie within the
stereoscopic depth of field.

The Kern-Paillard Instrument

The photographic instrument has been
built as an accessory for the HI 6 De Luxe
Paillard Camera. It is a compact as-
sembly screwed to the turret in place
of an ordinary lens ; it is automatically
centered with respect to the axis of

Fig. 6. Left- and right-eye Stereo images
on standard 16mm movie film.

rotation of the turret, to prevent differ-
ences in height between the left-hand
and right-hand images. The instrument
comprises two Yvar lenses,/ = 12.5mm,
aperture 1/2.8, with parallel optical axes
5.3mm apart. The normal base of 64
mm is obtained by a system of prisms
placed in front of the lenses (see Fig. 5).

The two homologous images are
located side by side on the 1 6mm film,
and together occupy one 16mm frame
(see Fig. 6).

The lenses are universally focused and
adjusted to their hyperfocal distance. If
we assume a circle of diffusion of 1/50
mm on the film, the depth of field of
definition is 5 = 2.8/50 = 0.056mm on
the print. The hyperfocal distance is
therefore

X = f2/S = 156.25/0.056 = 2790mm,

or 2.8 m. The lenses being adjusted for
2.8 m, good definition can be obtained
from 1.4 m to infinity at full aperture.
Now we have seen that the stereoscopic
depth of field permits us to photograph
from 1.6 m to infinity. The universal-
focus lens adjusted to hyperfocal distance
is thus adequate for all cases.

The projection instrument takes the
place of the lens of a standard 16mm
projector. It comprises 2 Petzval lenses,
/ = 20 mm, aperture 1/1.6, whose opti-
cal axes are parallel and 5.6 mm apart
(Fig. 7) ; the projection windows are cen-
tered with respect to these axes. In front
of each of these two lenses, there is a
polarizer; the planes of polarization of

522

December 1952 Journal of the SMPTE VoL 59

Kg. 7.

EH:

Schematic drawing of projection lens, showing f:1.6 lenses of Petzval type
and polarizing filters. The optical axes are separated by 5.6 mm.

the two polarizers are oriented at right
angles and at 45° to the horizontal so
that the film can be viewed with polariz-
ing spectacles available on the market,
for example Polaroid 3-D Picture Viewer.
The projection screen must preserve the
polarization of light. A metallized screen
coated with an aluminum-base varnish
is satisfactory.

We saw, in our discussion of stereo-
scopic depth of field, that the projection
window should be located in space near
a plane 3.2 m from the camera. Sup-
pose we are photographing a point A at
3 m from the camera with camera lenses
5.3 mm apart, focal length 12.5 mm,
base 64 mm. The two homologous
images A ' of A on the film will be

(64/3000)12.5 - 5.3 = 5.57

apart. The two projection windows
should therefore be 5.57 mm or about
5.6 mm, between centers, in order for
the plane of their stereoscopic image to
appear to merge with the plane of A.
The optical axes of the two projection
lenses are likewise 5.6 mm apart. Under
these circumstances, the planes at 3 m
from the camera will coincide on the
screen within 5.6 mm, regardless of the
distance from the projector to the
screen ; it would be possible to eliminate
the projection windows and bound the
picture with the edges of the screen itself.

The choice of focal lengths of the
camera and projector lenses places the
spectator at a distance of

D' = (1 2.5/20) ATP = 0.625*p

from the screen, or about two-thirds the
screen-projector distance, for correct
vision of the image.

Thus the Kern-Paillard instrument is
a standard-base instrument in which
judicious choice of focal lengths of camera
and projector lenses affords vision ap-
proximating that of natural relief to a
maximum number of spectators. The
distances between the lenses are such
that the image may be bounded either
by means of the edges of the screen or
by masking the projection lenses; in
either case, the stereoscopic image ap-
pears to be bounded by a window about
3 m from the spectator. Anything
photographed between 3 m and infinity
appears behind this window; anything
photographed between 1.5 m and 3 m
appears between the window and the
spectator. Photographing subjects closer
than 1.5 m will result in emergence from
the stereoscopic depth of field, and is
inadvisable without the use of accessories
which modify the convergence of axes
and focusing of the Kern-Paillard system
as they have been described in this
article.

Eugene Millet: Depth Effect in Motion Pictures

523

Screen Brightness Committee Report

By W. W. LOZIER, Committee Chairman

A HE LAST REPORT of the Screen Bright-
ness Committee presented at the April
1950 meeting of the Society1 related a
number of items receiving the attention
of the committee. This report will
summarize our progress to date and will
outline some of our future plans.

7. Subcommittee on Meters and Methods
of Measurement: This group under the
chairmanship of F. J. Kolb, Jr., has
made a thorough study of the measure-
ment of screen brightness and related
factors. Specifications have been set
up on the range of the variables which
will need to be covered by various types
of instruments. The report by this
Subcommittee has been accepted by
the Screen Brightness Committee and
recommended for early publication in
the Journal.

2. Subcommittee on Projection Screens:
This group under the chairmanship of
Leonard Satz is engaged in the prepara-
tion of standards covering the brightness
and whiteness characteristics of motion
picture screens. The old War Standards
of 1945 are being used as a basis of
departure.

3. Subcommittee on Illumination Practices:
This is a new group recently set up under
the chairmanship of A. J. Hatch, Jr.,

Presented on October 9, 1952, at the
Society's Convention at Washington, D.G.,
by W. W. Lozier, National Carbon Com-
pany, Division of Union Carbide and
Carbon Corp., Fostoria, Ohio.

for the purpose of establishing recom-
mended practices concerning distribu-
tion of illumination on the motion
picture screens.

Theater Survey of Screen Brightness: The
Committee has completed a survey of
screen brightness and related informa-
tion in 125 indoor theaters widely dis-
tributed over the United States and
in 18 West Coast studio review rooms
used for viewing 35mm motion pictures.
These data have been reported at the
two 1951 meetings of the Society,2*3 and
have been published in the Journal. This
survey has given us a good summary
of screen illumination practices in a
representative cross-section of the
theaters in this country. This informa-
tion is being used in our further activities
looking toward improvement of theater
screen illumination.

The Committee hopes to survey a
number of representative outdoor
theaters during 1953 to obtain informa-
tion on screen illumination practices in
these installations.

Revision of Screen Brightness Standard:
The currently applicable American
Standard on Screen Brightness, Z22.39-
1944, has been modified4 to include
only indoor theaters and therefore
exempts outdoor theaters from the pro-
visions of this Standard. The revised
standard has been recommended to the
ASA for adoption as an American
Standard.

524

December 1952 Journal of the SMPTE Vol. 59

Preferred Conditions for Viewing Motion
Pictures: Our Committee has concerned
itself with the fundamental problem of
determination and exposition of the
preferred conditions for viewing motion
pictures. The Committee has en-
couraged discussion of the history and
important factors having technical bear-
ing on this problem. A summary of
these matters was published last year in
the Journal by one of our committee
members.5

The Committee arranged and spon-
sored a Symposium on Screen Viewing
Factors at the Spring 1951 Convention
of the Society. The papers presented at
the symposium were published in the
September 1951 Journal6 and contain
much information pertinent to the
determination of preferred viewing con-
ditions. There are indications that our
efforts are bearing fruit and that new
interest has been stimulated in the
experimental determination of some of
these factors and further important
revelations can be expected.

References

1. W. W. Lozier, Chairman, "Screen
Brightness Committee Report," Jour.
SMPTE, 54: 756-757, June 1950.

2. W. W. Lozier, Chairman, "Report ori
Screen Brightness Committee Theater
Survey," Jour. SMPTE, 57: 238-246,
Sept. 1951.

3. W. W. Lozier, Chairman, "Further
Report on Screen Brightness Committee
Theater Survey," Jour. SMPTE, 57:
11-15, Nov. 1951.

4. "Revision of Screen Brightness Stand-
ard," Jour. SMPTE, 58: 452, May
1952.

5. F. J. Kolb, Jr., "The scientific basis for
establishing brightness of motion picture
screens," Jour. SMPTE, 56: 433-442,
April 1951.

6. Symposium on Screen Viewing Factors
(6 papers), Jour. SMPTE, 57: 185-237,
Sept. 1951.

The Committee

W. W. Lozier,
H. J. Benham
F. E. Carlson
M. H. Chamberlin

E. R. Geib

L. D. Grignon
A. J. Hatch
L. B. Isaac
W. F. Kelley

F. J. Kolb
L. J. Patton

Chairman
O. W. Richards
Leonard Satz
Ben Schlanger
Allen Stimson

C. R. Underhill
G. H. Walter
H. E. White

A. T. Williams

D. L. Williams

Reaffirmation — PH22.50-1952
16mm Projector Reel Spindles

ASA rules require periodic review of all American Standards. In accord with this
procedure, the 16mm and 8mm Motion Pictures Committee and the Standards
Committee have recently reviewed Z22. 50-1 946 and reaffirmed it without change.
The appropriate ASA committees have now approved this reaffirmation and the
standard is therefore published on the following page as a validated 1952 standard.

W. W. Lozier: Screen Brightness Report

525

American Standard

Reel Spindles

for 1 6-Millimeter Motion Picture Projectors

R't. V. -S fat. Off.

PH22. 50-1952

1. Round Section

1.1 The round section of 16-mm motion pic-
ture projector reel spindles shall have a fin-
ished diameter of 0.31 2 rh 0.003 inch (7.925
db 0.076 mm).

2. Square Section

2.1 The square section of 16-mm motion
picture projector reel spindles, including fin-
ish, shall be 0.312 ±0.003 inch (7.925 ±
0.076 mm) across the flats. Measurements
across the flats shall be made in mutually
perpendicular directions

3. Cumulative Effect of
Eccentricity

3.1 The cumulative effect of eccentricity of
the round and square sections of the spindles,
looseness and misalignment of the bearing,
or other mechanical imperfections shall not
cause the flange of a tight-fitting reel to de-
part from the ideal plane by more than 40
minutes of arc

3.2 A suitable gage for determining the
cumulative effect of eccentricity consists of a
hub, with coaxial square and round holes
whose respective sides and diameter are
equal in length, and a flange of suitable
stiffness whose diameter is equal to that of
an 800-foot reel flange, 10.5 inches (266.7
mm). The flange should be permanently
joined to the hub so that its face is perpen-
dicular to the axis of the hub with not more
than 0.003 inch (0.076 mm) runout. The. hub
shall be provided with a thumbscrew for
clamping the hub to the reel spindle so that
one side of the round and square holes shall
come in contact with the corresponding
round and square sections of the reel spindle.

4. Reel Position on Spindles

4.1 The design of spindles shall be such that
reels are kept under constant lateral pres-
sure against a shoulder on the spindle. The
part forming this shoulder need not be integ-
ral with the spindle. However, in such event,
it shall be securely fastened to the spindle so
so that the two parts rotate together-

Approved March 19, 1946, by the American Standards Association

526

December 1952 Journal of the SMPTE Vol. 59

Standards PH22.5, PH22.12 and PH22.93
Related to 16mm and 35mm Low-Shrink Film

Two REVISED American Standards and
one Proposed Standard are published on
the following pages for three month
trial and criticism. All comments
should be sent to Henry Kogel, SMPTE
Staff Engineer, prior to April 1, 1953.
If no adverse comments are received, the
three proposals will then be submitted to
ASA Sectional Committee PH22 for
further processing as American Stand-
ards.

The introduction of safety base of a
low-shrink type removes some of the
problems of film dimensions but has
introduced two slight difficulties. To
take care of these difficulties the Film
Dimensions Committee has recom-
mended modifications in the dimensional
standards for 16mm film (PH22.5 and
PH22.12) and has introduced a new
standard (PH22.93) for 35mm film to
be used as negative material on the
sprocket-type printer.

In the case of 16mm film the intro-
duction of low-shrink type base produced
an increase in the number of cases where
film has jammed in the camera gate.
Investigation showed this increase to be
due to the fact that many camera manu-
facturers had produced gates which
would pass film only if the width of the
film was appreciably less than the upper
limit (0.630 in.) of the cutting and
perforating tolerance. Now, the low-
shrink type of film, even though
originally slit within these tolerances,
would swell at high humidities just as
much as the older type with the result
that its width at the time of use might
well exceed the tolerance. This trouble

rarely occurred with the older type of
film because its characteristics were
such that it would shrink enough by the
time it reached the camera to compensate
for any possible swelling at high humidi-
ties. The Committee recommends,
therefore, an alternate standard slitting
width of 0.628 in. ± 0.001 in. to be
used with low-shrink film.

The Committee calls special attention
to the fact that the act of writing the
standard this way does not represent a
decrease in the actual width of film as
used by the customer. Manufacturers
of apparatus should not use this change in
dimension as a reason for changing the
width of film gates.

In the case of 35mm film the same
reasoning might apply but since no actual
difficulties have been reported, the Com-
mittee does not wish to make a change in
the nominal width of the film. Another
difficulty, however, has been introduced.
This difficulty occurs only on film which
is to be used on sprocket type printers.

It will be recalled that the negative
film on a sprocket-type printer must be
shorter in pitch than the positive film if
the two are to travel together around the
sprocket without slippage relative to
each other. For most printers this
difference in length corresponds to a
shrinkage of about 0.3%. Now, the
negative film, such as was formerly used
when nitrate film base was generally
used, would shrink to approximately
this value by the time it was ready for
making release prints. Not much
difficulty was encountered, therefore,
arising from the slippage between nega-

December 1952 Journal of the SMPTE Vol. 59

527

tive and positive films on sprocket-type
printers. With low-shrink safety base,
however, sufficient shrinkage did not
occur. It was found desirable, therefore,
to "pre-shrink" the film by perforating
it at a slightly shorter pitch than that
previously used. The pitch selected was
0.1866 in. This is approximately 0.2%
less than standard pitch instead of 0.3%
as required by theory. It is found in
practice, however, that this pitch pro-
duces satisfactory prints even when no
shrinkage at all has occurred and still
allows a margin for any shrinkage that
is likely to occur later. It also introduces
a minimum change in the action of the

film in the camera. Tests have shown
that cameras can take film of this pitch
quite as well as film of the standard pitch.
The case of master positive and
duplicating negative is not completely
solved by this new standard. Each one
of these is used in the printer on the
outside of the arc when the image is
printed on to it and on the inside of the
arc when the image is printed from it.
No single pitch, therefore, can take care
of both of these cases. In actual practice
it is generally found satisfactory to use
standard pitch for the master positive,
short pitch for the duplicating negative
and to do all the printing on continuous
printers. — E. K. Carver.

528

December 1952 Journal of the SMPTE VoL 59

Proposed American Standard

Dimensions for

16mm Double-Perforated

Motion Picture Film

PH22.5

P. 1 Of ? pp.

Dimensions

Inches

Millimeters

0.629 ± 0.001

15.98 =t 0.03

0.3000 ± 0.0005

7.620 ± 0.013

0.0720 ± 0.0004

1.83 ±0.01

0.0500 ± 0.0004

1.27 ±0.01

0.036 ^ 0.002

0.91 ± 0.05

Not > 0.001

Not > 0.025

0.413 ±0.001

10.490 ± 0.025

30.00 ± 0.03

762.00 ± 0.76

0.010

0.25

These dimensions and tolerances apply to negative and positive raw stock
immediately after cutting and perforating.

*For low-shrink film as defined in Appendix 2, A shall be 0.628 ± 0.001 and
E shall be 0.0355 ± 0.0020 in.

fin any group of four consecutive perforations, the maximum difference of
pitch shall not exceed 0.001 in. and should be as much smaller as possible.

$This dimension represents the length of any 100 consecutive perforation
intervals.

NOT APPROVED

December 1952 Journal of the SMPTE Vol. 59

529

Proposed American Standard

Dimensions for

16mm Double-Perforated

Motion Picture Film

PH22.5

Revision of
Z22.5-1947

P. 2 of 7 pp.

Appendix 1

The dimensions given in this standard rep-
resent the practice of film manufacturers in
that the dimensions and tolerances are for film
immediately after perforation. The puncher,
and dies themselves are made to tolerances
considerably smaller than those given, but
owing to the fact that film is a plastic mate-
rial, the dimensions of the slit and perforated
film never agree exactly with the dimensions
of the punches and dies. Shrinkage of the
film, due to change in moisture content or
loss of residual solvents, invariably results in
a change in these dimensions during the life
of the film. This change is generally uniform
throughout the roll.

The uniformity of perforation is one of the
most important of the variables affecting
steadiness of projection.

Variations in pitch from roll to roll are of
little significance compared to variations from
one sprocket hole to the next. Actually, it is
the maximum variation from one sprocket
hole to the next within any small group that
is important. This is one of the reasons for
the method of specifying uniformity in dimen-
sion B.

Appendix 2

In the early days of 16mm film the safety
base used for this film had the characteristic
of shrinking very rapidly to a certain fairly
definite amount and then not shrinking much
more. Although this film tended to swell at
high humidities, nevertheless the shrinkage
that occurred in the package before the user
received the film was always at least as great
as any swell that might occur due to high
humidities at the time of use. This meant that
the user never encountered film, even at high
humidities, that had greater width than that
specified in the standards. This meant that
camera and projector manufacturers seldom

ran into trouble so long as their film gates
would readily pass film at the upper limit of
the slitting tolerances, namely 0.630 in.

Within the past few years, however, a
safety base with lower shrinkage characteris-
tics began to be used. Although this film was
less susceptible than the previous film to swell-
ing at high humidities, nevertheless the shrink-
age characteristics were low enough so that
this shrinkage did not always compensate for
the swell at high humidities.

For this reason film slit at the mid point of
the tolerance for width, namely 0.629 in.,
would occasionally swell at high humidities
to such an extent that it would bind in film
gates designed to pass film with the width of
0.630 in. The manufacturers, therefore, were
compelled to slit at the lower edge of the
tolerance permitted by the American Stand-
ard. Variations in their slitting width, how-
ever, sometimes produced film slit below the
limits of the standard.

For this reason an alternate standard has
been adopted for this low-shrink film in order
that the manufacturers may slit within the
standard and still produce film which does not
exceed 0.630 in. even at high humidities.

For the purpose of this specification, low-
shrink film base is film base which, when
coated with emulsion and any other normal
coating treatment, perforated, kept in the
manufacturer's sealed container for 6 months,
exposed, processed, and stored exposed to
air not to exceed 30 days at 65 to 75 F and
50 to 60% relative humidity and measured
under like conditions of temperature and
humidity, shall have shrunk not more than
0.2% from its original dimension at the time
of perforating. The final measurement should
be made after conditioning the film for 24
hours to a humidity of 55 — 5%.

This definition of low-shrink film is to be
used as a guide to film manufacturers, and
departure therefrom shall not be cause for
rejection of the film.

NOT APPROVED

530

December 1952 Journal of the SMPTE JVol. 59

Proposed American Standard

Dimensions for

16mm Single-Perforated

Motion Picture Film

PH22.12

Revision of
Z22. 12-1 947

-1

oil

P. 1 of 2 pp.

Dimensions

Inches

Millimeters

tB
C
D
*E
U
R

0.629 ± O.OOl
0.3000 ± 0.0005
0.0720 ± 0.0004
0.0500 ± 0.0004
0.036 ± 0.002
30.00 ± 0.03
O.OIO

15.98 ± 0.03
7.620 ±0.01 3
1.83 ±0.01
1.27 ±0.01
0.91 ± 0.05
762.00 ± 0.76
0.25

These dimensions and tolerances apply to negative and positive raw stock
immediately after cutting and perforating.

*For low-shrink film as defined in Appendix 2.. A shall be 0.628 ± 0.001 and
E shall be 0.0355 ± 0.0020 in.

fin any group of four consecutive perforations, the maximum difference. of
pitch shall not exceed 0.001 in. and should be as much smaller as possible.

tThis dimension represents the length of any 100 consecutive perforation
intervals.

NOT APPROVED

December 1952 Journal of the SMPTE Vol. 59

531

Proposed American Standard

Dimensions for

16mm Single-Perforated

Motion Picture Film

PH22.12

Revision of
Z22. 12-1 947

Appendix 1

The dimensions given in this standard rep-
resent the practice of film manufacturers in
that the dimensions and tolerances are for film
immediately after perforation. The punches
and dies themselves are made to tolerances
considerably smaller than those given, but
owing to the fact that film is a plastic mate-
rial, the dimensions of the slit and perforated
film never agree exactly with the dimensions
of the punches and dies. Shrinkage of the
film, due to change in moisture content or
loss of residual solvents, invariably results in
a change in Ihese dimensions during the life
of the film. This change is generally uniform
throughout the roll.

The uniformity of perforation is one of the
most important of the variables affecting
steadiness of projection.

Variations in pitch from roll to roll are cf
little significance compared to variations from
one sprocket hole to the next. Actually, it is
the maximum variation from one sprocket
hole to the next within any small group that
is important. This is one of the reasons for
the method of specifying uniformity in dimen-
sion B.

Appendix 2

P. 2 of 2 pp.

ran into trouble so long as their film gates
would readily pass film at the upper limit of
the slitting tolerances, namely 0.630 in.

For the purpose of this specification, low-
shrink film base is film base which, when
coated with emulsion and any other normal
coating treatment, perforated, kept in the
manufacturer's sealed container for 6 months,
exposed, processed, and stored exposed to
air not to exceed 30 days at 65 to 75 F and
50 to 60%, relative humidity and measured
under like conditions of temperature and
humidity, shall have shrunk not more than
0.2% from its original dimension at the time
of perforating. The final measurement should
be made after conditioning the film for 24
hours to a humidity of 55 — 5%.

This definition of low-shrink film is to" be
used as a guide to film manufacturers, and
departure therefrom shall not be cause for
rejection of the film.

NOT APPROVED

532

December 1952 Journal of the SMPTE Vol.59

Proposed American Standard

Dimensions for

35mm Motion Picture Short-Pitch
Negative Film

PH22.93

P. 1 of 2 pp.

90^-

:g~ xmsj

Dimensions

Inches

Millimeters

1.377 ± 0.001

34.98 ± 0.03

0.1866 ± 0.0005

4.74 0± 0.013

0.1100 ± 0.0004

2.794 ± 0.01

0.073 ± 0.0004

1.85 ± 0.01

0.079 ± 0.002

2.01 =t 0.05

Not > 0.001

Not > 0.025

0.082

2.08

0.999 ± 0.002

25.37 ± 0.05

18.66 ± 0.015

474.00 ± 0.38

These dimensions and tolerances apply to low-shrink negative raw stock
immediately after cutting and perforating.

This film is used for motion picture negatives and certain special processes.
* A calculated value for a dimension not measured routinely in production.

| This dimension represents the length of any 100 consecutive perforation
intervals.

This standard is based on American Standard Z22. 34-1 949 and differs only in the
values of B and L and the addition of a second Appendix.

NOT APPROVED

December 1952 Journal of the SMPTE Vol. 59

533

Proposed American Standard

Dimensions for

35mm Motion Picture Short-Pitch
Negative Film

PH22.93

Appendix 1

The dimensions given in this standard rep-
resent the practice of film manufacturers in
that the dimensions and tolerances are for film
immediately after perforation. The punches
and dies themselves are made to tolerances
considerably smaller than those given, but
owing to the fact that film is a plastic mate-
rial, the dimensions of the slit and perforated
film never agree exactly with the dimensions
of the punches and dies. Shrinkage of the
film, due to change in moisture content or
loss of residual solvents, invariably results in
a change in these dimensions during the life
of the film. This change is generally uniform
throughout the roll.

The uniformity of perforation is one of the
most important of the variables affecting
steadiness of projection.

Appendix 2

Most motion picture film is printed on
sprocket-type printers. Maximum steadiness
and definition are secured on a sprocket-type

P. 2 of 2 pp.

printer when the negative film is somewhat
shorter in pitch than the positive stock.

For many years, this difference in pitch has
come about due to shrinkage of the negative
film base on processing and aging.

There are currently becoming available
new low-shrink film bases which do not shrink
sufficiently to provide the necessary pitch dif-
ferential between negative and print stock
for proper printing on sprocket-type printers.
This standard is intended to give dimensions
for perforating low-shrink film material so
that it will have, as nearly as possible, opti-
mum dimensions at the time of printing.

This definition of low-shrink film is to be
used as a guide to film manufacturers, and
departure therefrom shall not be cause for
rejection of the film.

NOT APPROVED

534

December 1952 Journal of the SMPTE Vol. 59

73d Semiannual Convention

A meeting of the Papers Committee at sions will be shown in the Advance Notice

Washington on October 9, during the of the Convention scheduled to be mailed

72d Convention, laid general plans for to members on March 2d.

the Spring Convention to be held at the Deadlines established by Papers Com-

Los Angeles Statler, April 27 - May 1. mittee Chairman Bill Rivers and 73d

Several aims were espoused and some Program Chairman Ralph Lovell are:

sessions planned. Inasmuch as the Na- Authors' Forms and Abstracts due on

tional Association of Radio and Television February 16; manuscripts due on March

Broadcasters will meet at Los Angeles ' , , f

Blank forms can now be obtained from
during the early part of that week, the anyone Qn ^ Papers Gommittee) but it

SMPTE television sessions will be held on ig preferable that you work with the one

Thursday and Friday, contrary to the nearest you. The complete roster of the

arrangement of recent convention pro- Committee will be published in the next

grams. The arrangement of all the ses- Journal.

The Chairman and Vice-Chairmen are:

Chairman: W. H. Rivers, Eastman Kodak Co., 342 Madison Ave., New York 17.
73d Convention Program Chairman: Ralph E. Lovell, 2743 Veteran Ave., West Los Angeles

64, Calif.

For Washington: J. E. Aiken, 116 N. Galveston St., Arlington 3, Va.
For Chicago: Geo. W. Colburn, 164 N. Wacker Dr., Chicago 6, 111.
For High-Speed Photography: Carlos H. Elmer, 410B Forrestal St., China Lake, Calif.
For Canada: G. G. Graham, National Film Board of Canada, John St., Ottawa, Canada.
For New York: E. Arthur Hungerford, Jr., Campfire Rd., Chappaqua, N.Y.

Awards

The Society serves its field in one way, among others, by an attempt to recognize formally
important contributions by individuals. Several awards are conferred annually upon
those whose work has been considered significant in their particular fields of interest.
Those who were selected during 1952 were presented awards during the Fall Convention
of the Society in Washington, D.C. Their names and awards are listed here.

As has been done in past years there were published earlier this year, in April, the
recommendations, citations and former recipients of the Progress Medal Award, the
Samuel L. Warner Memorial Award, the Journal Award and the David Sarnoff Award.

New Fellows of the Society

President Mole formally inducted the following as new Fellows of the Society:
John Arnold, Metro-Goldwyn-Mayer Studios, Culver City, Calif.
E. E. Blake, Council Kinematograph Manufacturers Association of Great Britain and

Kodak Ltd., London

O. L. Dupy, Metro-Goldwyn-Mayer Studios, Culver City, Calif.
Karl Freund, Photo Research Corp., Burbank, Calif.
Edgar Gretener, Dr. Edgar Gretener A.G., Zurich, Switzerland
W. T. Hanson, Jr., Eastman Kodak Co., Rochester, N.Y.
C. E. Heppberger, National Carbon Co., Chicago

535

President Peter Mole is at the -left. Award recipients next in order shown are:
Axel G. Jensen, the David Sarnoff Gold Medal Award; Wadsworth Pohl who ac-
cepted the Samuel L. Warner Memorial Award on behalf of Herbert T. Kalmus;
John I. Crabtree, the Progress Medal; and D. L. MacAdam, the Journal Award.

Henry J. Hood, Eastman Kodak Co., Rochester, N.Y.

A. G. Jensen, Bell Telephone Laboratories, Murray Hill, N.J.

.Klaus Landsberg, KTLA Television Productions, Hollywood, Calif.

E. H. Reichard, Consolidated Film Industries, Hollywood, Calif.

A. C. Robertson, Eastman Kodak Co., Rochester, N.Y.

Ben Schlanger, Consultant, New York

John G. Stott, Du-Art Film Laboratories, New York

E. W. Templin, Westrex Corp., Hollywood, Calif.

Journal Awards

The Journal Award went to D. L. MacAdam of the Research Laboratory, Eastman
Kodak Co., Rochester, N.Y., for his "Quality of Color Reproduction" which was pub-
lished in May 1951.

Franklin C. Williams of the Research Laboratory, Eastman Kodak Co., Rochester,
N.Y., received honorable mention for his "Current Problems in the Sensitometry of Color
Materials and Processes" which appeared in the Journal for January 1951.

Honorable mention was conferred on Otto H. Schade, Tube Dept., Radio Corporation
of America, Harrison, N.J., for "Image Gradation, Graininess and Sharpness in Tele-
vision and Motion Picture Systems — Part I : Image Structure and Transfer Charac-
teristics" which appeared in the February 1951 Journal.

536

William C. Kunzmann who has
been Convention Vice-President
since time memorial of this Society
was presented a gold card of Life
Membership "in grateful recogni-
tion of 36 years of enthusiastic
participation and inspired leader-
ship in the work of the Society."
Shown in the usual order are
Editorial Vice-President John
Frayne, Bill Kunzmann and Presi-
dent Peter Mole. Next are pic-
tures salvaged from old lantern
slides depicting Bill and his activi-
ties at a somewhat earlier stage of
his career.

New Society Formed

At a meeting at the Hotel Astor. New Yoik, October 2nd, 3icl and
1th, the Society of Motion Picture Engineers was formed. The member-
ship includes men who are closely connected with the development of the
engineering and of motion pictuie woik and the society has for its main
object the standardization of the industry. \V. C. Kurzman of the Sales
Department is a member of the Committee on Illumination Devalopmc-nt.
At the organization meeting C. Francis Jenkins, of Washington. D. C..
was elected president. The next meeting of the society will be held at
Atlantic City some time in Maich, at which a number of pnpeis will he
pi esented.

537

Progress Medal

John I. Crabtree, head of the photographic chemistry department of Kodak Research
Laboratories, received the Progress Medal "for his outstanding contribution in the field
of photographic chemistry, motion picture processing and processing equipment." The
formal presentation was made by D. B. Joy, Chairman of the Progress Medal Award
Committee, as follows:

"He was born and educated in England and started his professional work as a Research
Chemist with the Eastman Kodak Company in Rochester in 1913. He became a natural-
ized United States citizen in 1924. He founded the photographic chemistry department
of Kodak Research Laboratories in 1913 and is still its head. From 1916 to 1938 he also
was in charge of the motion picture film developing department. He has conducted and
supervised research in many fields of photography including the chemistry of development
and fixation, methods of processing photographic materials, the use of desensitizers, stains
and markings on photographic materials, preparation and use of flash powders, tinting
and toning of lantern slides and motion picture films, the corrosive effect of photographic
solutions on photographic apparatus, tropical processing, silver recovery, compounding
of package chemicals, storage of photographic records, and effective methods of washing
photographic materials. He has devoted much of his attention to the technique of motion
picture processing.

"A particularly important piece of research concerned the chemistry of the stop bath
and especially of the fixing bath. Recent very valuable work has been done in his depart-
ment on agents for "sequestering" calcium and iron in developers, on replenishment
systems for developers, on rapid processing at high temperatures, on the preparation of
concentrated liquid developers, and on the design of special processing equipment.

"He has been author and co-author of some 150 papers and two books and has been
granted 30 United States patents, covering a wide variety of subjects. His articles have
been published in many countries and several have been reprinted as handbooks.

"He has been a member of this Society for more than 25 years. He was President of
the Society in 1930 and 1931, during which time he was largely instrumental in establish-
ing the Journal on a monthly basis, the system of Sustaining Memberships, the Journal
Award and this Progress Medal Award. His vivid discussions of papers have enlivened
many a Society Meeting. He was a member of the Board of Governors for many years
and served as Chairman of several committees and of the Board of Editors.

"He has been an active member of many other scientific societies.

"For nearly forty years, John I. Crabtree has worked diligently at his chosen profession
of photographic chemistry. Much of the advancement of knowledge of general photo-
graphic and motion picture processing reactions and techniques can be traced directly
to his researches and that of colleagues under his supervision."

Samuel L. Warner Memorial Award

Herbert T. Kalmus, President and General Manager of Technicolor Motion Picture
Corp., was awarded the Samuel L. Warner Memorial Award. President Mole first
spoke of the awarding as follows :

"As one who comes from Hollywood, I am taking the liberty of saying a few words of
my own on this award. In the early twenties, an obscure scientist was struggling in
Boston to perfect a color formula for motion picture film which was destined one day to
revolutionize the motion picture industry. This scientist, against innumerable odds and
financial setbacks, was persistent, however, and finally conquered these obstacles to give
to the world of motion pictures natural color as we know it today — Technicolor.

"For bringing color to motion pictures, Herbert Kalmus must be credited as one of the
savers of the motion picture boxoffice. Color came at a time when the public was tiring

538

of black-and-white films and both producers and exhibitors needed something new to
attract patrons to the theater. As one who richly deserves this high honor from our
Society, Dr. Herbert T. Kalmus now receives the Samuel L. Warner Memorial Award,
accepted on his behalf by Mr. Wadsworth Pohl, his associate."

The citation prepared by the Committee, of which Glenn L. Dimmick is Chairman,
was as follows:

"No man, over the past 20 years, has so consistently contributed to the technical quality
of motion pictures as Dr. Herbert T. Kalmus. Almost without exception, the biggest
grossers since Gone With the Wind have been pictures made in 'Color by Technicolor.'
Indeed, good color of any type, in the eyes of the public, is called Technicolor. It is
today the standard by which other color processes are judged.

Dr. Kalmus, over the years, has maintained the highest practicable color standards
and has always recognized the value of research and engineering toward this end. While
maintaining these standards of quality, the cost of not only release prints but set lighting
costs have been reduced step by step as faster-type emulsions were made available to
picture producers. During the last war, Technicolor's ability to 'blow up' the 16mm
Kodachrome footage of the Armed Forces to 35mm film for showing to the public in
theaters was a great aid to morale and public information in those critical times. If it
had not been for the war and its retarding effect on civilian development, Technicolor's
single-film Monopack would have been available sooner to supplant the three-negative
process. Dr. Kalmus hoped as early as 1940 to bring it into wide use and its availability
will undoubtedly be greater in the immediate future.

"Technicolor's perfection in the last few years of the inbibition process of making top
quality 16mm color prints in quantity at reasonable cost is a distinct contribution to the
16mm field. The quality of both picture and sound of these prints and the development
of the techniques of making the separate sound negatives for mass production by the
35mm32mm method contributes a great deal to the excellence of the 16mm sound.

"Dr. Kalmus, through his personal and active direction of his company, has been
instrumental in creating the boxoffice truism that 'good color makes a good picture a
still better picture.'

"For further information on Dr. Kalmus, I refer to the article in the Saturday Evening
Post of October 22, 1949, 'Mr. Technicolor,' by Frank J. Taylor. Dr. Kalmus was
given the Society's Progress Medal for 1938 and the citation was presented on pages 556
to 560 of the December 1938 Journal."

David Sarnoff Gold Medal Award

Axel G. Jensen was presented the David Sarnoff Gold Medal Award "for his manifold
contributions to the promulgating of monochrome and color television engineering
standards, and for his work on the improvement of the quality of television pictures
obtained from motion picture film." Pierre Mertz was Chairman of the Committee
which made this citation:

"Axel G. Jensen was born and educated in Copenhagen, Denmark, until coming to
Columbia University in 1921 for graduate work.

"His professional career began in 1922 when he joined what is now the Research
Department of the Bell Telephone Laboratories. Since 1938 he has been engaged in
research work in television equipment and systems. In particular he has been responsible
for the development of a high-quality testing link which, employing motion picture film,
can be used as a research tool for the evaluation of methods and systems for television
transmission, and of the influence of component elements on the transmission quality.
As a part of this he has been in charge of work on a succession of test film scanners, cul-
minating in a development which was presented before the Society last year. He has

539

also been responsible for considerable miscellaneous research work on electrical, optical
and visual problems connected with television systems.

"Mr. Jensen has taken part in many industry committees, particularly many com-
mittees promulgating engineering standards for television as a result of their deliberations.
He took an active part in the committee work of the first NTSG in 1941, from which came
the engineering standards in monochrome television which are still largely in use today.
He continued to take an active part in the television activities of RTPB from 1944 to
1948, and of panels of JTAG. In the second NTSG, established in 1950, he has been a
member of several panels and is now vice-chairman of Panel 12 on Color System Analysis.
He has been chairman of the IRE-RTMA-SMPTE Television Coordinating Committee
in 1950-51; vice-chairman of the IRE Standards Committee in 1949-50, and chairman
in 1951 ; chairman of the IRE Television Committee in 1948; and chairman of the IRE
Television Systems Committee in 1949-51. He was elected a Fellow of the IRE in 1942,
and Governor of the SMPTE in 1952. He has just finished an extensive lecture tour,
in the United States and Europe, describing the fundamentals of color television trans-
mission and of the various systems which can be used to achieve it. In the course of it
he was awarded the G. A. Hagemann Gold Medal by the Royal Technical University of
Denmark.

"In the Bell Telephone Laboratories Mr. Jensen has recently been promoted from
Engineer in Charge of Television Research, to Director of Television Research. He
holds ten issued patents and has published a number of papers, the most recent being,
in coauthor-ship with R. E. Graham and C. F. Mattke, on a "Continuous Motion Picture
Projector for Use in Television Film Scanning," in the January 1952 Journal."

Board of Governors Meeting

Meeting on October 5 at Washington,
the Board gave a considerable portion of
its attention to information from the
Executive Committee, reported by Execu-
tive Vice-President Barnett and Executive
Secretary Nemec.

The publication of proposed amend-
ments to the Bylaws in the August Journal
was noted. (These were voted approved
at the Society's Business Meeting on
October 6.) Plans for continued study of
test film costs were briefly discussed and the
Society's success in restoring the mailing
of the Journal to the proper (lowest cost)
category was noted.

A lively, detailed and constructive
discussion about membership service
quality, costs and promotion held the
Board's attention for nearly two hours,
with every officer and governor contribut-
ing reports of the needs of television, film
producer, high-speed photography and
other interests. Specific suggestions in
the notes for follow-up by the staff were
tabbed as from Messrs. Aiken, D'Arcy,

Heppberger, Mole, Neu, Shaner, Sponable,
Stifle and Townsley. (Material helpful
to television engineers has since been
planned. The complete roster of member
and nonmember high-speed photography
registrants has been mimeographed and
circulated to the High-Speed Photography
Committee for their help in obtaining new
members. The brochure describing the
Society for prospective members ,is now
revised.) A six-page membership cost
study was read by Executive Secretary
Nemec on behalf of the Executive Com-
mittee. This study was accepted as the
record of the past three years and as a
basis for a continuing record and guidance
for the Board.

Reports by the respective vice-presidents
were welcomed and approved as in good
order by the Board.

A change in the Administrative Practices
was approved as presented as follows in
the report by Editorial Vice-President
Frayne:

540

"Because the Board of Editors as pres-
ently comprised of 18 members is no more
than adequate, the Administrative Prac-
tices should be brought up to date by
changing the present stipulation of 'seven
Fellows and Active members,' to: 'The
Editorial Vice-President upon taking office
shall appoint the chairman of the Board of
Editors and the members of the Board.
The latter shall consist of not less than 12
members of the Society in good standing
and shall be representative of all the

various branches and interests of the motion
picture and television industry.' "

Reports of Section Chairmen Hepp-
berger, Shaner and Stifle contained a new
element in greater strength: regional
organizations established at San Francisco
and Dallas and proposed in Atlanta. (A
report of the San Francisco Subsection has
been given in the October 1952 Journal
and a brief report of the Atlantic Coast
Section Regional Meeting was published in
the September 1952 Journal.)

New Officers

At the close of the October 5 Board Meet-
ing, Secretary Robert M. Corbin reported
the results of the Society election for 1952.
The following were elected for two-year
terms beginning January 1, 1953:

Herbert Barnett, President
John G. Frayne, Executive Vice-President
Norwood L. Simmons, Editorial Vice-
President

John W. Servies, Convention Vice-Presi-
dent

Edward S. Seeley, Secretary
Frank E. Carlson, Governor, Central
Gordon A. Chambers, Governor, East
LeRoy M. Bearing, Governor, Pacific
William A. Mueller, Governor, Pacific
Charles L. Townsend, Governor, East
Malcolm G. Townsley, Governor, Central

By action of the Board of Governors
during its previous meeting in July, Henry
Hood was appointed to fill a vacancy in
the office of Engineering Vice-President
that was created by the resignation of
F. T. Bowditch. Henry's term extends
to December 31, 1953.

The Section elections made the following
officers and new members of the Board of
Managers :

Atlantic Coast Section

William H. Offenhauser, Jr., Chairman
Emerson Yorke, Secretary-Treasurer
Russell C. Holslag, Manager, 1953-1954
Milton H. Searle, Manager, 1953-1954
R. T. Van Niman, Manager, 1953-1954

Central Section

C. E. Heppberger, Chairman, reelected
James L. Wassell, Secretary-Treasurer,

reelected

Paul Ireland, Manager, 1953-1954
William P. Kusak, Manager, 1953-1954
John S. Powers, Manager, 1953-1954

Pacific Coast Section

Vaughn C. Shaner, Chairman, reelected
Philip G. Caldwell, Secretary-Treasurer,

reelected

Ralph Lovell, Manager, 1953-1954
Hollis Moyse, Manager, 1953-1954
Herbert Pangborn, Manager, 1953-1954

K. Kenneth Miura

The Student Chapter at the
University of Southern Cali-
fornia earlier this year elected
K. Kenneth Miura its Chair-
man, and Richard Pollster
its Secretary-Treasurer.

Richard Polister

541

Organization of the Southwest Subsection

Activities of the recently formed Southwest
Subsection began formally on the evening
of October 23 in the studios of WBAP-TV,
Fort Worth, Texas. C. E. Heppberger
presided over the meeting and advised
about the operation of a subsection . There
were present 13 members and 23 guests.

Elected as the subsection's first roster of
officers were:
Bruce Howard, Chairman ;
Hugh V. Jamieson, Jr., Vice-Chairman and
Secretary-Treasurer ;

Engineering Activities

/. L. Miller, Program Chairman; and
George Mayer, Membership Chairman.

Future meetings are tentatively
scheduled :

January 16, Friday evening, in Dallas;
March 16, Monday evening, in Fort

Worth; and
May 20, Wednesday evening, in Dallas.

Members will be advised by letter
confirming the dates and exact place of
the meetings. — Hugh V. Jamieson, Jr., 3825
Bryan St., Dallas 4, Tex.

72d Convention This is a continuation
of the report on the
meetings of Engineering Committees at the
72d Convention in Washington, D.C. See
the November 1952 Journal for the first
part of this story.

16mm and 8mm Six American Stand-
Motion Pictures ards, listed below, have
been under active re-
view for some time:

PH22.9, 16mm Double-Perforated Motion
Picture Film — Usage in Camera ;

PH22.10, 16mm Double-Perforated Mo-
tion Picture Film — Usage in Projector ;

PH22.15, 16mm Single-Perforated Motion
Picture Film — Usage in Camera ;

PH22.16, 16mm Single-Perforated Motion
Picture Film — Usage in Projector ;

PH22.21, 8mm Motion Picture Film —
Usage in Camera;

PH22.22, 8mm Motion Picture Film —
Usage in Projector.

At this meeting it was agreed to draft
further revisions of the first two standards,
eliminate "guided edge" specification from
the next two standards, and approve the
last two standards without further change.

The ballot on the proposed standard,
A and B Windings of 16mm Raw Stock
Film, PH22.75, was reported as virtually
complete without any negative votes.
The ballot was therefore closed with an
affirmative recommendation to the Stand-
ards Committee for further processing as an
American Standard.

Magnetic Recording The widespread

Subcommittee development and

use of magnetic

sound tracks demand a companion test
film and standards program. Such a
program, under way for some time, has
now been launched with full force.

The magnetic recording proposals for
16mm and 35mm-17£mm film, PH22.86
and PH22.87, have cleared all the ap-
propriate Society committees and are
presently under review by ASA Sectional
Committee PH22.

Agreement was reached on the dimen-
sions of the magnetic coating of the 8mm
proposal, PH22.88, for immediate con-
sideration by the Sound Committee.

Similar approval was given to five
proposed standards on magnetic test
films, listed below:
SMPTE 509, 16mm Magnetic Flutter

Test Film;

SMPTE 510, 35mm and 17imm Mag-
netic Flutter Test Film;
SMPTE 511, Azimuth Alignment Test
Film for 17^mm and 35mm Film With
Magnetic Coating;

SMPTE 512, Azimuth Check Loop on
17|mm and 35mm Film With Magnetic
Coating;

SMPTE 513, Azimuth Test Film for Fully
Coated Magnetic 16mm Single-Per-
forated Motion Picture Film.

A subcommittee was then formed to
study existing magnetic recording equip-
ment with a view toward standardizing
the reproducer characteristics.

542

Finally, with an eye toward the future,
attention was called to the potentialities
of half photographic/ half magnetic track
on 16mm film and magnetic track sub-
stituted for photographic on 35mm film.

Sound This meeting followed on the
heels of the above Subcommittee
meeting but in actuality the two meetings
were held jointly. The Sound Committee
now approved for letter ballot the six
proposals approved by the Subcommittee
and a seventh on 200-mil magnetic coating
of 16mm single perforated film (SMPTE
544) submitted by the Subcommittee some
time prior to this meeting.

In addition it was agreed to revise the
three test film standards listed below.
The revision would permit elimination of
the identification leader and substitution
of titles printed lengthwise in the picture
area. This would increase the usable
test film footage by about 25% without
increasing its cost.
Z22.42-1946, 16mm 5000- and 7000-Cycle

Sound Focusing Test Films;
Z22.45-1946, 16mm 400-Cycle Signal

Level Test Films;
Z22. 57-1 947, 16mm Buzz Track Test Films.

Stereo This committee was formed in
March 1952 with immediate
attention devoted to development of a
standard nomenclature and compilation
of a bibliography. Prior to this first meet-
ing the committee was very active in
nomenclature activity via the mails. The
entire meeting was therefore devoted to
reviewing this activity and working out
word for word the meanings of some of
the more controversial, complex terms.

In briefly commenting on the bibliog-
raphy project, John Norling, Chairman,
stated that progress was being made and
that a first draft would soon be issued to
the committee for review.

Television Film This meeting had been
Equipment called for only one

reason: to expedite ac-
tion on dimensional standards for the re-
corded and reproduced area of televised
motion pictures. Differences had de-
veloped between East and West Coast
thinking on this question which had pre-
vented standardization to date.

The advantages and disadvantages of

both proposals were thoroughly aired and
a compromise proposal was offered for
consideration. It was finally agreed to
submit the latter proposal for letter ballot
of the full committee. The vital dimen-
sions of all three proposals are:

35 mm Record Reproduce

East .609 X .812 .582 X .776

West .619 X .825 .600 X .800

Compromise .612 X .816 .594 X .792

16mm

East . 288 X . 384 . 270 X . 360

West .288 X .384 .279 X .372

Compromise . 285 X . 380 . 276 X . 368

Color This was the first meeting of this
committee under its new Chair-
man, Dr. J. P. Weiss. The committee
reviewed the state of the art and concluded
that color was still in the early stages of
development, which precludes any stand-
ards work at this time. It was noted,
however, that comprehensive reports on
various aspects of the field — for example,
the published report "Principles of Color
Sensitometry" — are considered very useful
and desirable, and plans were made to
further stimulate such activity.

High-Speed A high priority was given
Photography to the question of develop-
ing a dictionary of terms
peculiar to high speed photography and
a subcommittee headed by Morton Sul-
tanoff was appointed to begin active work
on this.

The ASA Exposure Index also came up
for discussion and it was considered highly
desirable to extend film ratings to cover
the range of exposures from a millisecond
to a microsecond. This is no simple
matter and the question was referred to
ASA Sectional Committee PH2 for study
and action.

The meeting closed with Carlos Elmer
accepting the responsibility of the high-
speed photography papers program for
the Spring Convention in Los Angeles.

Meeting Reports For those who are
interested in more de-
tailed information concerning any of the
above reported engineering committee
meetings, a copy of the particular meeting
report is available upon request. — Henry
Kogel, Staff Engineer.

543

Book Reviews

Storage Tubes

and Their Basic Principles

By M. Knoll and B. Kazan. Published
(1952) by John Wiley, 440 Fourth Ave.,
New York 16. 143 pp. 34 illus. 6X9
in. Price $3.00.

Presumably the first text devoted ex-
clusively to storage tubes, this book is
useful to anyone concerned with the field.
Of particular interest to television and
motion picture engineers is the treatment
of the iconoscope, the image orthicon and
their relatives as particular cases of the
genus storage-tube.

The writers first treat fundamentals,
the electron bombarded "floating" surface,
then definitions and basic operational
methods. This is followed by a lucid
treatment of the details of 23 individual
storage tubes, suitably classified as to
type. Ninety-nine references comprise the
Bibliography, with the helpful innovation
of a brief resume of the gist of each. Be-
sides providing additional information
this prevents "wild-goose-chases" after
apparently promising titles.

Because the tubes are each treated in the
same methodical manner, similarities
and differences are easily grasped and can
be quickly located when the book is used
as a reference work. Storage tubes suit-
able for use with electronic computers
are, of course, included, including the
interesting case of the kinescope with the
external electrode of metal foil.

Co-author Knoll is well known in the
field and is responsible for four tubes that
are treated impartially along with the
rest.

The book is devoid of mathematical
expressions, this aspect being treated in
many of the citedA references. Informative
circuit diagrams and the essentials of con-
struction of the tubes are given.

In view of the modest price, anyone
who must have an understanding of these
devices can hardly afford to be without the
book. — Harry R. Lubcke, Consulting Engi-
neer, 2443 Creston Way, Hollywood 28,
Calif.

1952-53 Motion Picture and
Television Almanac

Published (1952) by Quigley Publications,
1270 Sixth Ave., New York 20, N.Y.,
i-1 + 1010 pp. (including advt.), thumb
indexed, 6 X 9 in. Price $5.00.

This is another in the imposing procession
of these annual reference volumes, this
one giving an increased attention to the
television field. Much of the preliminary
work and planning for this volume was
done by the late Maurice D. Kann who
died on May 15, 1952.

With from three to eleven subsections
where appropriate, the volume contains
these sections:
Who's Who in Motion Pictures and

Television
Corporations
Theatre Circuits
Drive-In Theatres
Television and Radio
Pictures
Services

Theatre Equipment Services and Materials
Organizations
The Government Case
Codes and Censorship
The World Market
The Industry in Great Britain
The Press
Non-Theatrical Motion Pictures

Although not a technical or engineering
book, this is a valuable and obvious source
for data on many business and facilities
aspects of the Society's field as well as a
help in another amusement activity —
settling a discussion. — V.A.

High Speed Photography Issue

This is a special number of the Scientific
Section of The Photographic Journal for
Sept.-Oct. 1952. The release describing
this issue advises:

"It is claimed that this publication
brings this very important subject com-
pletely up to date and it is a source of
reference which every firm, government
department, laboratory, educational insti-

544

tution, and individual interested in this
field should have.

"It is quite obvious that a number of
scientific workers and institutions, not
directly specializing in photography and
the kindred sciences, do not yet realize
the necessity of maintaining a complete
set of "Section B" of The Photographic
Journal. With the approach of the So-
ciety's Centenary — 1953 — [this point
should be emphasized]. Since its founda-
tion on 20 January 1853, this world- wide
organization has fostered all applications of
photography, kinematography, photoen-
graving, and radiography since their very
inception as we know them today. We
confidently expect wide recognition of the
work performed by this Society during the
past one hundred years."

Those who attended the International
Symposium on High-Speed Photography
at the SMPTE Convention in October will
recognize at least two respected acquaint-

Current Literature

ances among the contributors to The
Photographic Journal's special issue:

R. H. J. Brown, "Flash Cinematography"

W. D. Chesterman and G. T. Peck, "A
Synchronized Flash-Discharge System
for High-Speed 35mm Cinematography"

J. S. Courtney-Pratt, "Image Converter
Tubes and Their Application to High
Speed Photography"

R. A. Chippendale, "Image Converter
Techniques Applied to High Speed
Photography"

K. D. Froome, "An Electronically Oper-
ated Kerr Cell Shutter"

J. M. Meek and R. C. Turnock, "Electro-
Optical Shutters as Applied to the
Study of Electrical Discharges"

This issue is noted on its cover as costing
five shillings. Annual rates and other
information should be requested from
The Royal Photographic Society, 16
Princes Gate, London, S.W.7.

The Editors present for convenient reference a list of articles dealing with subjects cognate to motion
picture engineering published in a number of selected journals. Photostatic or microfilm copies of
articles in magazines that are available may be obtained from The Library of Congress, Washington,
D.G., or from the New York Public Library, New York, N.Y., at prevailing rates.

American Cinematographer

vol. 33, Aug. 1952

Hollywood Launches 3-D Film Production (p.
336) J. Biroc

The Vistascope . . . New Tool for Motion Picture
Production (p. 338) L. L. Ryder

"Anistration" . . . Streamlined Animation Tech-
nique (p. 340) A. Rowan

Background Projection Photography (p. 342)
C. L. Anderson

High-Speed Cinematography (p. 343) J. H.
Waddell

vol. 33, Sept. 1952
WarnerColor — Newest of Color Film Process

(p. 384) E. B. DuPar
Miniatures in Motion Picture Production (p.

386) A. Rowan

Camera Fill Lights (p. 388) F. Foster
Lighting for High-Speed Motion Pictures (389)

J. H. Waddell
Wheels that Still Turn Backward (p. 390) R. H.

Cricks
Filming the TV Dramatic Featurette (p. 392)

H. A. Lightman
Now . . . Magnetic Sound for All Cine Films

(p. 394) J. Forbes

Bild und Ton

vol. 5, Sept. 1952
Die Projektierung eingebauter Lichtspieltheater

in Moskau (p. 271)
Schaden am 35-mm-Kino-Film (p. 279) H.

Mager

British Kinematography

vol. 21, July 1952

Magnetic Sound on 16mm Edge-Coated Film;
A Short Review of a Current Trend (p. 15)

vol. 21, Sept. 1952

A Test to Measure the Flammability of Kine-
matograph Safety Film (p. 61) R. W. Pickard
Latensification (p. 67) P. Raibaud

Electrical Communication

vol. 29, Sept. 1952

Low-noise Traveling- Wave Tube (p. 234) A. G.
Peifer, P. Parzen and J. H. Bryant

Electronics

vol. 25, Aug. 1952

Improving TV System Transient Response (p.
110-113) John Ruston

vol. 25, Oct. 1952

A Phase Indicator for Color Television (p. 112)
K. Schlesinger and L. W. Nero

545

International Projectionist

vol. 27, July 1952
Heart of the Projector Mechanism (p. 5) R. A.

Mitchell
Fox Unveils Eidophor, Arc-Lit Color TV (p. 14)

vol. 27, Aug. 1952

Heart of the Projector Mechanism, Pt. II (p. 8)
R. A. Mitchell

vol. 27, Sept. 1952
Heart of the Projector Mechanism, Pt. Ill (p. 5)

R. A. Mitchell
Stereosound Enhances Eidophor TV (p. 11)

Kino-Technik

no. 7, July 1952
Der neue Tonschmalfilmprojektor Elektor 16T3

(p. 171)
Infrarotfilm in der wissenschaftlicken Kine-

matographie (p. 172) J. Rieck
Jetzt auch Stereofilm im eigenen Heim (p. 177)

H. Luscher

no. 9, Sept. 1952
Berlins Anteil an der deutschen Filmindustrie

(p. 208) H. Muting
Aus der Arbeit der Berliner kinotechnischen

Betriebe (p. 209)

Akustik im Tonfilmtheater (p. 214) W. Bausch
"Filmosound 202" schafft neue Moglichkeiten fur

den 16-mm-Film (p. 216) W. Beyer
Tonaufnahmegerate und Mischanlage der West-
ern Electric (p. 218)

Storungen bei der Vorfiihrung von Tonfilmen
(p. 221) K. Braune and H. Tummel

Motion Picture Herald

vol. 188, Oct. 1952
(Better Theaters Section)
How the New Four-Inch Lenses Give a Brighter

Picture (p. 10) G. Gagliardi

Getting into the Drive-in Business, Pt. 8, Plan-
ning the Main Building (p. 11) W. P. Smith
This is Cinerama on Broadway (p. 14)

Proceedings of the I.R.E.

vol. 40, Aug. 1952

Requisite Color Bandwidth for Simultaneous
Color-Television Systems (p. 909-912) Knox
Mcllwain

Elimination of Moire Effects in Tri-Color Kine-
scopes (p. 916-923) E. G. Ramberg
Cathode-Ray Picture Tube With Low-Focusing
Voltage (p. 937-945) C. S. Szegho

vol. 40, Oct. 1952
An Experimental System for Slightly Delayed

Projection of Television Pictures (p. 1177) P.

Mandel
Gamma Correction in Constant Luminance

Color Television Systems (p. 1185) S. Apple-

baum

Radio and Television News

vol. 48, Aug. 1952

Cinemagnetic Recording (p. 46) A. C. Blaney
The TV Picture Tube (p. 50) W. Buchsbaum

Tele-Tech

vol. 11, Oct. 1952
Television Control Room Layout (p. 48) R. D.

Chipp

SMPTE Lapel Pins

The Society will have available for mailing after September 15, 1952, its gold and blue
enamel lapel pin, with a screw back. The pin is a £-in. reproduction of the Society
symbol — the film, sprocket and television tube — which appears on the Journal cover.
The price of the pin is $4.00, including Federal Tax; in New York City, add 3%
sales tax.

Obituary

Percy D. Brewster died on October 27 at his home at East Orange, N.J., after a long
illness. He had retired 12 years ago. His work as a motion picture engineer led him to
credit as the inventor of several color photographic processes, with 360 patents granted
to him. He was President of the Brewster Color Film Corp. of Newark, N. J., and of the
former Revelation Film Corp. of London.

He became a member of the Society of Motion Picture Engineers in 1929 and was made
a Fellow in 1934. He was cited by the Royal Society of London for his work in color
photography and was the first to make a color photograph of President Wilson. He was
graduated from Cornell University in 1906.

546

New Members

The following members have been added to the Society's rolls since those last published,
designations of grades are the same as those used in the 1952 MEMBERSHIP DIRECTORY.

The

Honorary (H)

Fellow (F)

Active (M)

Associate (A)

Student (S)

Adair, George P., Consulting Engineer, George
P. Adair Engineering Co., 1610 Eye St.,
N.W., Washington 6, B.C. (M)

Adler, Benjamin, Engineer, Adler Communica-
tions Laboratories, 1 LeFevre La., New
Rochelle, N.Y. (M)

Bras, Rene, President, Science Pictures, Inc.,

5 E. 57 St., New York, N.Y. (M)

Diner, Leo, Motion Picture Producer, 332

Golden Gate Ave., San Francisco, Calif. (M)
Ewing, Jasper G., Jr., Partner, Jasper Ewing &

Sons. Mail: 725 Poydras St., New Orleans,

La. (A)
Friedman, Jacob, Photographer, Emerson

Electric Manufacturing Co. Mail: 7010

Tulane, University City 5, Mo. (A)
Gallagher, James C., President, Gallagher

Films, Inc. Mail: 137 N. Oakland Ave.,

Green Bay, Wis. (A)
Gilreath, Walter W., District Manager, RCA

Service Co., Inc. Mail: 3732 Stanford St.,

Dallas 5, Tex. (M)
Goldman, Leslie A., Production Manager

(Motion Pictures), Tempo Productions, Inc.,

588 Fifth Ave., New York 36, N.Y. (A)
Hildebrandt, Carl E., Optical Field Technician,

Sandia Corp. Mail: 674 Sunset Dr., P.O.

Box 410, Brawley, Calif. (A)
Hill, Armin J., Research Physicist, Motion

Picture Research Council, 1421 North

Western Ave., Los Angeles 27, Calif. (M)
Inglis, Andrew F., Radio Engineer, Mclntosh

6 Inglis. Mail: 4619 Norwood Dr., Chevy
Chase, Md. (M)

Johnson, Howard R. H., Assistant to Deputy
Chief, Operations, Air Photographic &
Charting Service, 3701 North Broad St.,
Philadelphia, Pa. (A)

Johnston, Capt. Clint, Chief, Motion Picture &
Video Production Division, Air Photographic
& Charting Service, U.S. Air Force, 3701
N. Broad St., Philadelphia 40, Pa. (A)

Kaplan, Fred M., Geo. W. Colburn Laboratory,

Inc. Mail: 6508 Rockwell, Chicago 45, 111.
(A)

Lee, Harold V., President and Manager, Color-
vision, Inc., 129 W. Alameda Ave., Burbank,
Calif. (M)

Lewis, Jack, Owner, Jack Lewis Studios, 705
East Main St., Richmond 19, Va. (M)

Lohnes, Kenneth F., Cine Technician, Warner
Brothers Studio. Mail: 4604 Cahuenga
Blvd., North Hollywood, Calif. (A)

Mack, Donald, TV Sales Manager, Production
Assistant, Filmack Corp. Mail: 8626 Prairie
Rd., Skokie, 111. (M)

Oldershaw, Malcolm J., Consulting Engineer,
Canadian Marconi Co., Ltd., 2442 Trenton
Ave., Mount Royal, Quebec, Canada. (A)

Ottemiller, William H., Jr., Division Manager,
Quality Control, Television Picture Tube
Division, Sylvania Electric Products, Inc.
Mail: R.D. #1, Seneca Falls, N.Y. (M)

Pike, Rowland, District Manager, Ansco
Division, General Aniline & Film Corp.
Mail: 7125 Maple Ave., Takoma Park 12,
Md. (M)

Powis, Chauncey G., TV Engineer, KDYL-
TV. Mail: 59^ Hillside Ave., Salt Lake
City, Utah. (A)

Rowley, Basil G. H., Technical Representative,
Marconi's Wireless Telegraph Co., Ltd.,
23-25 Beaver St., New York 4, N.Y. (A)

Sandwick, Luther M., Vice-President, Wilcox-
Gay Corp., Charlotte, Mich. (M)

Sproul, Thomas G., Film Technician, Con-
solidated Film Industries. Mail: 4461 Morse
Ave., North Hollywood, Calif. (A)

CHANGES IN GRADE
Bury, John L., Jr., (S) to (A)
Gausman, Harvey E., (A) to (M)
MacDonald, Joseph W., (S) to (A)
Wicker, L. P., (A) to (M)

SMPTE Officers and Committees: The roster of Society Officers and the
Committee Chairmen and Members were published in the April Journal.

547

Chemical Corner

Edited by Irving M. Ewig for the Society's Laboratory Practice Committee. Suggestions should
be sent to Society headquarters marked for the attention of Mr. Ewig. Neither the Society nor the
Editor assumes any responsibility for the validity of the statements contained in this column. They
are intended as suggestions for further investigation by interested persons.

Foam Prevention Tributyl phosphate
has good antifoaming
properties and in addition is colorless and
odorless. This product is marketed by
Apex Division of Food Machinery and
Chemical Corp., Niro, W. Va.

Substitute British Kinematography has an
for Metol article in the February 1952
issue (vol. 20, no. 2) describ-
ing a substitute for metol. It is 1-phenyl
3-pyrazolidene. It is white and odorless;
and persons sensitive to metol poisoning
are reported unaffected by this so-called
Phenidone. Like metol it is sensitive
to pH and is soft working when used alone.
In combination with hydroquinone it
gives a more rapid, less grainy image and
produces less fog. It also yields a high
contrast with hydroquinone and has a
lower exhaustion rate. It is possible to
match a metol-hydroquinone developer
with a phenidone-hydroquinone developer.

Construction of An interesting article,
Water Purifier "Pure water for your
darkroom," in American
Photography, (vol. 45, 341-346, June 1951),
by H. F. Walton, describes a method
for constructing a water-purification, ion-
exchange unit. All that is required is some
laboratory glassware and commercial resins.

Try It Before A method for rapid
You Buy It identification of nickel

alloys, stainless steels,
etc., might be of value in the motion
picture laboratory where the question of
materials of construction of processing
equipment often comes up. Such a quick
test procedure has been described in a
pamphlet by Henry B. Lee of Eastman
Kodak and published as Special Technical
Bulletin #98 by the American Society
for Testing Materials, 1916 Race St.,
Philadelphia 3, Pa. The metals or groups
of metals for which methods of testing are
described are nickel, monel metal, inconel,

stainless steel #316, other chrome nickel,
nickel stainless steels, straight chromium
stainless steels as a class, etc. All the
requirements for testing are seven common
chemicals, a stirring rod, a medicine
dropper, a porcelain spot plate and an
abrasive cloth.

Tank Cleaning Advice L. B. Russell
Chemicals, Inc.,

of 60 Orange St., Bloomfield, N.J., markets
a chemical preparation called "Wizz"
which is used for cleaning developing tanks.
Reported safe to handle, noncorrosive and
useful with any type of material, it is dis-
solved in water. The solution is kept over-
night in the developer tank which is then
washed out thoroughly to leave the tank
free of chemical deposit and crustation.
Periodic treatment of developer tanks will
add to uniformity of the developer and
lengthen its life, eliminate dirt problems
and generally improve processing.

Film Processing A series of articles by
Chemistry various authorities deal-

ing with some funda-
mental chemistry of film processing ap-
peared in British Kinematography, vol. 20,
no. 2, Feb. 1952. One of these articles
discusses the various chemical constituents
of a developer and their roles; the chemi-
cal reactions of a developer and the prod-
ucts formed . The matter of the dependence
of the rate of replenishment on the amount
of bromide that can be tolerated in the
developer is discussed. It is also pointed
out that the work of development is per-
formed by metol while hydroquinone serves
to reverse the oxidized metol back to its
original functional state and thereby
becomes oxidized itself. Therefore, the
maintenance of the metol concentration
in the developer is easy compared to
that of hydroquinone. Some suggestions
about electrolytic recovery of silver and
the regeneration of hypo are also discussed.

548

Testing the Exhaustion L. G. Sandys

of a Fixing Bath presents his

views about how

to increase the efficiency of fixing baths
and methods of testing in an article,
"Efficiency and conservation of fixing
baths," published in The British Journal
of Photography, Vol. 98, pp. 662-3, Dec.
1951. If a yellow precipitate persists
upon the addition of a 4% potassium
iodide solution to ten parts of the fixer,
it is exhausted. This can be confirmed
by agitation with a paddle of some kind
and if a lasting froth develops it indicates
that the bath is spent.

Temperature Control for
Film Processing Solutions

U.S. Patent
#2,584,294
assigned to
Remington Rand describes a procedure
for isolating the developer and fixer sections
of a processing machine by a compartment
and circulating heated air from the drying
compartment through this chamber.

Filter-Aid Aid During the present strike

at Johns Manville, users

of their Celite filter aids find themselves in

a difficult situation. Perhaps the Brown

Company of Berlin, N.H., have a solution
to this problem with their "Solka-floc"
which they claim (1) prevents "leak
through" in the filtration process, (2)
enables high flow rates, (3) enables con-
trolled porosity in the filter cake and (4)
reduces labor cost by diminishing the
number of times filter presses have to be
cleaned. The general sales office is at
150 Causeway St., Boston, Mass.

New Method of VPI (Vapor Phase In-
Rust Prevention hibitor) is chemically
known as dicyclohexyl
ammonium nitrate and is manufactured
commercially by Monsanto Chemical
Company. By vaporizing and allowing it
to deposit on the product, it is reported to
prevent corrosion. It may be used by
impregnating paper and lining a drawer
with this paper. This will prevent corro-
sion of anything kept in this drawer.
However, its methods of application are
numerous. It is nonflammable and will
reach areas where usual corrosion pre-
ventatives cannot be applied. One gram
of VPI provides protection for one cubic
foot of metal if properly wrapped to
prevent loss of vapor.

Meetings

American Society of Photogrammetry, Annual Meeting, Jan. 14-16, Shoreham Hotel,

Washington, D. C.

American Institute of Electrical Engineers (Symposium on the Science of Music and Its

Reproduction — 3d Lecture), Jan. 15, Engineering Societies Bldg., New York, N. Y.

Society of Motion Picture and Television Engineers, Southwest Subsection Meeting,

Jan. 16, Dallas, Tex.

American Institute of Electrical Engineers, Winter General Meeting, Jan. 19-23, New

York, N. Y.

American Physical Society, Annual Meeting, Jan. 22-24, Cambridge, Mass.
Institute of Radio Engineers Conference and Electronics Show, 5th Annual Southwestern

Conference and Show, Feb. 5-7, San Antonio, Tex.

American Institute of Electrical Engineers (Symposium on the Science of Music and Its

Reproduction — 4th Lecture), Feb. 20, Engineering Societies Bldg., New York, N. Y.

National Electrical Manufacturers Association, Mar. 9-12, Edgewater Beach Hotel,

Chicago, 111.

Society of Motion Picture and Television Engineers, Southwest Subsection Meeting

Mar. 16, Fort Worth, Tex.

Duke University, Durham, N.C.

549

American Physical Society, Apr. 30-May 2, Washington, D.G.
Acoustical Society of America, May 7-9, Hotel Warwick, Philadelphia, Pa.
Society of Motion Picture and Television Engineers, Southwest Subsection Meeting,

May 20, Dallas, Tex.

American Physical Society, June 18-20, Rochester, N.Y.

American Institute of Electrical Engineers, Summer General Meeting, June 29- July 3,

Atlantic City, N.J.

Biological Photographic Association, 23d Annual Meeting, Aug. 31-Sept. 3, Hotel Statler,

Los Angeles, Calif.

The Royal Photographic Society's Centenary, International Conference on the Science
and Applications of Photography, Sept. 19-25, London, England

Theatre Equipment and Supply Manufacturers' Association Convention (in conjunction
with Theatre Equipment Dealers' Association and Theatre Owners of America),

Oct. 31-Nov. 4, Conrad Hilton Hotel, Chicago, 111.

Theatre Owners of America, Annual Convention and Trade Show, Nov. 1-5, Chicago, 111.
National Electrical Manufacturers Association, Nov. 9-12, Haddon Hall Hotel, Atlantic

City, N.J.

Employment Service

Positions Wanted

Audio- Visual School of Education Gradu-
ate: M.A., Audio-Visual Education,
New York University. Sound background
in personnel and contact work, attractive,
single, personable. Prefer position New
York or New Jersey area. Spent 3 years
abroad, civilian, Special Services Director.
Miss Fredericka Appleby, 810 Broadway,
Newark, N.J. HUmboldt 5-4582.

Research, field engineering, manufac-
turing opportunity for B.S. Electrical
Engineering candidate, Jan. 1953; Scholar-
ship student, M.I.T.; studied in Germany,
1945-1950. Languages: German, Polish,
Russian and English. Some radio shop
experience; also M.I.T. Library and
Engineering Dept. Single, no dependents ;
Military Status, 5 A (over 26). Prefer

location in East. Joseph Liebermann,
513 Beacon St., Boston, Mass.

Position Available

Appearance Technology may not be a
new term but it is being pushed into the
light by Richard S. Hunter who announces
that he has formed Hunter Associates
Laboratory, 5421 Brier Ridge Rd., Falls
Church, Va., a consulting group devoted
exclusively to appearance and related
optical properties of materials — color,
diffuse reflectance, gloss or luster, turbidity,
haze, opacity and the like. Mr. Hunter,
who has left the position of Chief Optical
Engineer with the Henry A. Gardner
Laboratory at Bethesda, Md., reports
that his organization is equipped to test
materials for either routine or special
appearance properties and to design
appearance-testing instruments.

550

Papers Presented

at the Washington Convention, October 6-10

BY SESSIONS

MONDAY AFTERNOON — Television Session

J. E. Hayes, Canadian Broadcasting Corp., Montreal, Canada, "Television Facilities

of the Canadian Broadcasting Corporation."
R. D. Chipp, Du Mont Television Network, New York, "Film Projection Using Image

Orthicon Cameras."
L. L. Pourciau, General Precision Laboratory, Inc., Pleasantville, N.Y., "Television

Camera Equipment of Advanced Design."
W. E. Stewart, Radio Corporation of America, Engineering Products Division, Camden,

N.J., "New Professional Television Projector."

MONDAY EVENING — Television Session

William H. Offenhauser, Jr., New Canaan, Conn., "Nomenclature for Motion Pictures
and Television in the Society of Motion Picture and Television Engineers."

Pierre Mertz, Bell Telephone Laboratories, New York, "Influence of Echoes on Tele-
vision Transmission."

A. V. Loughren, Hazeltine Corp., Little Neck, L.I., N.Y., "The Accomplishments and
Recommendations of the National Television System Committee in the Field of
Color Television."

TUESDAY MORNING — Television Session

Mary Ellen Widdop, RCA Victor Division, Camden, N.J., "A Review of Work on
Dichroic Mirrors and Their Light-Dividing Characteristics."

Ralph E. Lovell, National Broadcasting Co., Hollywood, Calif., "Time-Zone Delay of
Television Programs by Means of Kinescope Recording."

Ralph E. Lovell and Robert M. Fraser, National Broadcasting Co., Hollywood and
New York, "Instrumentation and Sensitometry Employed in Kinescope Recording."

John S. Auld, Signal Corps Photo Center, Long Island City, N.Y., "Facilities and Em-
ployment of the Signal Corps Mobile Television System."

TUESDAY AFTERNOON — Television Session

Karl Freund, Photo Research Corp., Burbank, Calif., "Shooting Live Television Shows

on Film."
Ferenz Fodor, Filmcraft Productions, Hollywood, Calif., "Filmcraft's Camera Control

System."

551

TUESDAY EVENING — General Session

Leonard A. Herzig, Prestoseal Manufacturing Corp., Long Island City, N.Y., "Method
and Apparatus for Splicing Motion Picture Safety Film Without the Use of Cements
or Adhesives."

Gustav Jirouch, Cine-Television Equipment, Ltd., Kent, England, "The Robot Auto-
matic Film Splicer.'*

R. Kingslake (Committee Chairman), Eastman Kodak Co., Rochester, N.Y., ".Optics
Committee Report."

E. H. Bowlds, E. H. Bowlds Engineering Co., Los Angeles, Calif., "An Animation Stand

of New Design."

John A. Rodgers, Eastman Kodak Co., Rochester, N.Y., "Projector for 16mm Optical
and Magnetic Sound."

Ann Hyer, Division of Audio-Visual Education, National Education Association, Wash-
ington, D.C., "Planning Classrooms for Use of Audio-Visual Materials."

WEDNESDAY MORNING (Concurrent Sessions)
Film Processing Session

Leonhard Katz and William F. Esthimer, Raytheon Manufacturing Co., Newton, Mass.,
"Further Experiments in High-Speed Processing Using Turbulent Fluids."

F. Dana Miller, Eastman Kodak Co., Rochester, N.Y., "Rapid Drying of Normally

Processed Black-and-White Motion Picture Films."
Edward B. Krause and Joseph A. Tanney, S.O.S. Cinema Supply Corp., New York,

"The Bridgamatic Developing Machine."
E. K. Carver (Committee Chairman), Eastman Kodak Co., Rochester, N.Y., "Film

Dimensions Committee Report."
John Streiffert, Kodak Research Laboratories, Rochester, N.Y., "A Fast-Acting Exposure

Control System for Color Motion Picture Printing."
A. A. Duryea, T. J. Gaski and L. Mansfield, Pathe Laboratories, Inc., New York, "Film

Presentation of Various Productions on Eastman Negative-Positive Color Process."

High-Speed Photography Session

John H. Waddell, Wollensak Optical Co., Rochester, N.Y., "Introduction of the Sym-
posium and History of High-Speed Photography."

Richard O. Painter (Vice-Chairman), General Motors Proving Ground, Milford, Mich.,
"High-Speed Photography Committee Report."

Norman F. Barnes, General Electric Co., Schenectady, N.Y., "Optical Techniques for
Fluid Flow."

Major P. Naslin, French Laboratory of Armament, Paris, France, "Some Simple Elec-
tronic High-Speed Photographic and Cinematographic Devices."

R. M. Blunt, Institute of Industrial Research, University of Denver, Denver, Colo.,
"The Use of Photography in the Underground Explosion Test Program, 1951-1952."

WEDNESDAY NOON — High-Speed Photography Luncheon

A. C. Keller, Bell Telephone Laboratories, New York, Keynote Address, "The Eco-
nomics of High-Speed Photography."

552

WEDNESDAY AFTERNOON — High-Speed Photography Session

Louis F. Ehrke, Westinghouse Electric Corp., Bloomfield, N.J., "History of Ultra High,

Speed X-Ray Exposures and X-Ray Motion Pictures."
S. J. Jacobs, Naval Ordnance Laboratory, White Oak, Md., "Space-Time Resolution

as a Criterion for Comparing Ultra-High-Speed Photographs."
Roger Wilkinson, Bell Telephone Laboratories, New York, and Harry Romig, Hughes

Aircraft Co., Culver City, Calif., "Space-Time Relationships With Multiple Camera

Installations."
H. Schardin, Laboratoire de Recherches, Weil Am Rhein, Baden, Germany, "The

Development of High-Speed Photographic Techniques in Europe."
Morton Sultanoff, Terminal Ballistics Laboratory, Aberdeen Proving Ground, Md.

"Photographic Instrumentation in the Study of Explosive Reactions."

THURSDAY MORNING — High-Speed Photography Session

Harold E. Bauer and Webster Blake, Douglas Aircraft Co., Santa Monica, Calif., "The
Applications of Wide-Angle Optics to Moderately High-Speed Motion Picture
Cameras."

J. S. Courtney-Pratt, University of Cambridge, Cambridge, England, "Two New Methods
of High-Speed Photography."

H. W. Greenwood, Canadian Armament Research and Development Establishment,
Ottawa, Canada, "Information Discussion of Image-Con ver tors and Other Ballistic
Methods."

F. W. Bowditch, General Motors Corp., Detroit, "The Use of Motion Picture Photog-
raphy for Combustion Research."

Amy E. Griffin and Elmer E. Green, U.S. Naval Ordnance Test Station, China Lake
Calif., "Accuracy Limitations on the Use of High-Speed Metric Photography."

W. O. Johnson, E. I. du Pont de Nemours & Co., Wilmington, Del., "High-Speed
Photography in the Chemical Industry."

THURSDAY AFTERNOON (Concurrent Sessions)
General Session

R. D. Bennett, Technical Director of the Naval Ordnance Laboratory, White Oak, Md.,

"The Naval Ordnance Laboratory."
J. S. Watson, Jr., and S. A. Weinberg, University of Rochester School of Medicine and

Dentistry, Rochester, N.Y., "70mm Motion Picture Camera for X-Ray Motion

Pictures."
W. W. Lozier (Committee Chairman), National Carbon Co., Fostoria, Ohio, "Screen

Brightness Committee Report."
Armin J. Hill, Motion Picture Research Council, Hollywood, Calif., "A Simple Formula

for Taking Stereoscopic Motion Pictures."
Armin J. Hill, Motion Picture Research Council, Hollywood, Calif., "A First-Order

Approximation for the Mathematical Treatment of Diffusing Surfaces."
Allen Stimson and Edward H. Fee, General Electric Co., West Lynn, Mass., "Color

and Reflectance of Human Flesh."

High-Speed Photography Session

Harold C. Barr, Sandia Corp., Albuquerque, N.M., "High-Speed Photographic Instru-
mentation in Field Tests."

553

Berlyn Brixner, Los Alamos Scientific Laboratory, Los Alamos, N.M., "High-Speed,
Rotating-Mirror Frame Camera."

A. M. Erickson, Naval Ordnance Laboratory, White Oak, Md., "Photographic Instru-
mentation of Timing Systems."

H. Schardin, Weil Am Rhein, Baden, Germany, "High-Speed Spark Photography."

I. L. Stern and J. H. Foster, Material Laboratory, New York Naval Shipyard, Brooklyn,
N.Y., "High-Speed Photographic Techniques for the Study of the Welding Arc."

Charles T. Lakin, U.S. Naval Ordnance Test Station, Inyokern, Calif., "The 70-mm Test
Vehicle Recorder."

W. R. Stamp and R. P. Coghlan, Royal Naval Scientific Service, United Kingdom,
"Growth and Decay of Light Measured Photographically From Flash Discharge
Tubes."

W. D. Chesterman, Royal Naval Scientific Service, United Kingdom, "New Precision
Rotating Prism High-Speed Motion Picture Camera."

W. D. Chesterman, Royal Naval Scientific Service, United Kingdom, "Further De-
velopments in High-Speed Photography in England."

Carl G. Jennergren, Research Institute of National Defense, Stockholm, Sweden, "High-
Speed Photography in Sweden."

THURSDAY EVENING (Current Sessions)

Symposium on 16mm Equipment Maintenance

Bernard A. Cousino, Cousino, Inc., Toledo, Ohio, "Equipment Maintenance — Key to
Success."

Henry H. Wilson, Ampro Corp., Chicago, "Operation of a Manufacturer's Service
Organization."

Fred Whitney, SMPTE, New York, and R. A. House, Film Recording Group, RCA
Victor Division, Camden, N.J., "Test Films for 16mm Equipment Maintenance."

Thomas C. Sheehan, Visual Instruction Office, Washington Public Schools, Washington,
D.C., "Maintaining Visual Education Equipment in a Large City School System."

O. T. Bright, Bell & Howell Co., Chicago, "Selection, Training and Equipping Field
Service Stations for Repair of 16mm Projection Equipment."

Philip M. Cowett, Bureau of Ships, U.S. Navy Dept., Washington, D.C., "Navy Main-
tenance of 16mm Projection Equipment."

High-Speed Photography Session

Karl W. Maier, Springfield Armory, Springfield, Mass., "A Procedure for Complete

Analysis of High-Speed Motion Picture Data."
C. David Miller and Arthur Scharf, Battelle Memorial Institute, Columbus, Ohio, "An

Isotransport Camera for 100,000 Frames per Second."
Robert D. Shoberg, Army Ordnance Corp., White Sands Proving Ground, Las Cruces,

N.M., "High-Speed Instrumentation of Guided Missiles."
Kenneth Shaftan, J. A. Maurer, Inc., Long Island City, N.Y., "Progress in Photographic

Instrumentation in 1951."

FRIDAY MORNING (Concurrent Sessions)
Sound Recording and Reproduction

W. K. Grimwood and J. R. Horak, Kodak Research Laboratories, Rochester, N.Y.,
"Optimum Slit Height in Photographic Sound-Track Reproducers."

554

J. K. Milliard (Committee Chairman), Altec Lansing Corp., Beverly Hills, Calif., "Sound
Committee Report."

Robert Dressier and Albert Chesnes, Paramount Pictures Corp., New York, " Sound-on -
Film Recording Using Electro-Optic Crystal Techniques."

John G. Frayne, Westrex Corp., Hollywood, Calif., and J. P. Livadary, Columbia Pic-
tures Corp., Hollywood, Calif., "Dual Photomagnetic Intermediate Studio Record-
ing."

Maxwell A. Kerr, Navy Dept., Bureau of Ships, Washington, D.C., "16mm Release-
Print Inspection — Some Observations and Proposals."

High-Speed Photography Session

Joshua Fields, Louis Fields, Eleanor Gerlach and Myron Prinzmetal, Institute for Medical
Research, Cedars of Lebanon Hospital, Los Angeles, "High-Speed Cine-Electro-
cardiography . "

Willard E. Buck, Los Alamos Scientific Laboratory, Los Alamos, N.M., "Transient
Pressure Recording With a High-Speed Interferometer Camera."

Floyd Stratton and Kurt Stehling, Bell Aircraft Co., Buffalo, N.Y., "Applications of
High-Speed Photography in Rocket Motor Research."

Harry R. Clason, National Advisory Committee for Aeronautics, Langley Field, Va.,
"A Method of Lighting Large Fields for High-Speed Motion Picture Photography."

William P. Holloway, U.S. Naval Ordnance Test Station, Inyokern, Calif., "A Theod-
olite Method of Camera Calibration."

Earl Quinn, Eastman Kodak Co., Rochester, N.Y., "A Case History of a High-Speed
Tapping Operation."

FRIDAY AFTERNOON (Concurrent Sessions)

1 • Symposium on Magnetic Striping of Film

Edward Schmidt, Reeves Soundcraft Corp., Springdale, Conn., "Commercial Experi-
ences With Magnastripe Production."

B. L. Kaspin, A. Roberts, H. Robbins and R. L. Powers, Bell & Howell Co., Chicago,
"Magnetic Striping Techniques and Characteristics."

A. H. Persoon, Minnesota Mining and Manufacturing Co., St. Paul, Minn., "Magnetic
Striping of Photographic Film by the Laminating Process."

Thomas R. Dedell, Eastman Kodak Co., Rochester, N.Y., "Magnetic Sound Tracks for
Processed 16mm Motion Picture Film."

G. A. Del Valle and L. W. Ferber, RCA Victor Division, Camden, N.J., "Notes on
Wear of Magnetic Heads."

Ernest W. Franck, Reeves Soundcraft Corp., Springdale, Conn., "A Study of Drop-
Outs in Magnetic Film."

E. W. D'Arcy, De Vry Corp., Chicago, "Standardization Needs for 16mm Magnetic
Sound."

High-Speed Photography Session

David C. Gilkeson and A. E. Turula, Wollensak Optical Co., Rochester, N.Y., "Optical
Aids for High-Speed Photography."

Frederick P. Warrick, Frederick P. Warrick Co., Bloomfield Hills, Mich., "A High-
Speed Recording Camera Featuring Constant Film Velocity and Large Film Ca-
pacity."

John H. Waddell, Wollensak Optical Co., Rochester, N.Y., "Full-Frame 35mm Fastax
Camera."

M. Roganti, Wright-Patterson Air Force Base, Dayton, Ohio, "New Air Force Recording
Camera."

Myron A. Bondelid, U.S. Naval Ordnance Test Station, Inyokern, Calif., "The M-45
Tracking Camera."

Charles A. Hulcher, Charles A. Hulcher Co., Hampton, Va., "70mm High-Speed
Sequence Camera."

555

Binding of a Volume of Journals

THROUGH the cooperation of the Library
Binding Institute, an organization of
binderies which specializes in binding pub-
lications into volumes, arrangements have
been made to give information and assist-
ance to Society members who want to have
their Journals bound. This work may be
done in accordance with standards of mate-
rials and construction required for durabil-
ity, service and accessibility by college,
reference and public libraries. The Ameri-
can Library Association and the Library
Binding Institute have cooperated in pro-
mulgating "Minimum Specifications for
Glass A Library Binding" based on research
and production and performance experi-
ence.

A committee of the American Library
Association has certified responsible and
reliable library binderies which have
proved able to meet these specifications.
To obtain standard quality binding, simply
request Glass A binding at any certified
bindery. In obtaining price quotations,
state the three dimensions of the volume.

Names and addresses of certified bind-
eries in your area are available from the
Library Binding Institute, 501 Fifth Ave.,
New York 17, N.Y.

A library binder who specializes in
binding volumes such as those of this
Journal, and who has been selected as a
capable binder, for instance, by the
American Institute of Physics, is The
Book Shop Bindery, 308 West Randolph
St., Chicago 6, 111.

Before sending copies to the bindery:

1. Check for missing issues and check
each issue for defects, missing pages, etc.
Be sure to include the volume index.
(Beginning with Vol. 56, No. 6 of the

Journal carries a Volume Title Page and
Contents.)

2. Tie the six issues together carefully
and package so that nothing is crumpled or
torn.

3. Write out definite instructions giving
your preferences on the following points:

a. Color of binding (one of the following
standard colors should be selected: dark
green, dark blue, black, brown or medium
red).

b. Whether the paper covers are to be
bound into the volume.

c. An exact copy of the text to be lettered
in gold on the backbone. A common form
is:

Journal — 1 f in. from top

SMPTE [SMPE before 1950] — 2\ in.

from top

Vol. 00 — 4£ in. from bottom
1900 — 3f in. from bottom

d. If you have had Journals bound
before and want your set to match as
closely as possible, send a previous volume
as a sample. If you want an approximate
match, send a "rubbing" of the lettering on
a previous volume and indicate the color.

If satisfactory arrangements cannot be
made, or if there is any difficulty, advise
the Society office and steps will be taken in
cooperation with the Library Binding
Institute to assure you proper service.

As Part II of this issue, there is appended
a Volume Title Page with Volume Con-
tents to go at the front of the volume when
bound, and the Volume Index to go at the
back.

A microfilm edition of the Journal may
also be obtained by members or subscribers
by direct correspondence with University
Microfilms, 313 North First St., Ann Arbor,
Mich.

556

December 1952 Journal of the SMPTE Vol. 59

INDEX TO SUBJECTS

July — December 1952 • Volume 59

ACOUSTICS

Acoustic Problems at the "Waldbiihne"
Open-Air Sound Theater in Berlin,
Hans Simon Dec. pp. 512-516

Auditorium Specifically Designed for Tech-
nical Meetings, D. Max Beard and A.
M. Erickson Sept. pp. 205-211

ANIMATION

Animation for Individual Television Sta-
tions, Ernest F. Riser Oct. pp. 293-299

Drawing in Three Dimensions. for Anima-
tion and Stereoscopic Processes, Ernest
F. Riser Oct. pp. 287-292

ARCS

A-C High-Intensity Arc Slide Projector,
Arthur J. Hatch Oct. pp. 335-337

Continuous Arc Projector Light Meter,
Harry P. Brueggemann July pp. 40-43

BOOK REVIEWS

High-Speed Photography Issue (of The Photo-
graphic Journal) Dec. p. 544

1952-53 Motion Picture and Television
Almanac Dec. p. 544

Storage Tubes and Their Basic Principles,
by M. Knoll and B. Kazan (Reviewed
by Harry R. Lubcke Dec. p. 544

Color in Business, Science and Industry, by
Deane B. Judd (Reviewed by L. M.
Dearing) Oct. p. 357

Classrooms, No. 1 in series Planning Schools

for Use of Audio-Visual Materials, National

Education (Reviewed by D. F. Lyman)

Sept. pp. 241-242

Proceedings of the London Conference on
Optical Instruments 1950 (Reviewed by
O. W. Richards) Sept. p. 242

Technical Optics (Vol. II), by L. C. Martin

(Reviewed by Dr. John L. Maultbesch)

Sept. pp. 242-243

Focal Cinebooks, Focal Press' "How to"
series (Reviewed by Lloyd E. Varden)
Sept. p. 243

Proceedings of the National Electronics Con-
ference, Vol. 7 (Reviewed by H. I.
Zagor) July p. 77

Professional Training of Film Technicians, by

Jean Lods (Reviewed by George L.

George) July p. 78

Fluorescent Lighting, by W. Elenbaas et al.,

edited by G. Zwikker (Reviewed by C.

L. Amick) July p. 78

The Recording and Reproduction of Sound

(2d ed.), by Oliver Read (Reviewed by

Clyde R. Keith) July p. 78

CHEMICAL CORNER

Dec. p. 548

CINEMATOGRAPHY (see also HIGH-
SPEED PHOTOGRAPHY)

A Precision Color Temperature Meter for
Tungsten Illumination, G. H. Dawson,
D. E. Grant and H. F. Ott

Oct. pp. 309-312

Follow-Focus Device and Camera Blimp
for 16mm Professional Camera, Lee R.
Richardson and William N. Gaisford

Aug. pp. 118-124

COLOR

Use of Ansco Color Film in Commercial

Production, Reid H. Ray

Nov. pp. 406-409
Transmission Color in Camera Lenses,

Philip T. Scharf Sept. pp. 191-194

Integrating-Type Color Densitometer,

Frank P. Herrnfeld Sept. pp. 184-190

CURRENT LITERATURE

Sept. p. 246 Dec. p. 545

EDUCATION

Auditorium Specifically Designed for Tech-
nical Meetings, D. Max Beard and A. M.
Erickson Sept. pp. 205-211

Cameo Film Production Technique
Charles F. Hoban and James A. Moses
Sept. pp. 195-204

-Un commercial phonoregistrator bin-
aural — Interlingua Translation of
First Page of "A Commercial Binaural
Recorder," Alexander Code Aug. p. 108

International Auxiliary Language for Mo-
tion Pictures, Mary Bray Aug. p. 107

The Navy's Training Film Production
Program, Wilson R. Cronenwett and
William M. Timmons July pp. 49-57

December 1952 Journal of the SMPTE Vol.59

557

FILM
General

Proposed American Standard 35mm Mo-
tion Picture Short-Pitch Negative Film,
PH22.93 Dec. p. 527

Proposed American Standard Dimensions
for 16mm Single-Perforated Motion Pic-
ture Film, PH22.12 (Rev. Z22.12-1947)
Dec. p. 527

Proposed American Standard Dimensions

for 16mm Double-Perforated Motion

Picture Film, PH22.5 (Rev. Z22.5-1947)

Dec. p. 527

American Standard Edge Numberingl6mm
Motion Picture Film, PH22.83-1952

Nov. p. 427

American Standard Raw Stock Cores for
16mm Motion Picture Film, PH22.38-
1952 Nov. p. 427

Film Dimensions Committee Report, E. K.
Carver Nov. pp. 423-425

Use of Ansco Color Film in Commercial
Production, Reid H. Ray

Nov. pp. 406-409

Nonsilver Photographic Processes, Thomas
T. Hill July pp. 58-66

Educational, Documentary and Training

Animation for Individual Television Sta-
tions, Ernest F. Hiser Oct. pp. 293-299

Drawing in Three Dimensions for Anima-
tion and Stereoscopic Processes, Ernest
F. Hiser Oct. pp. 287-292

Cameo Film Production Technique,
Charles F. Hoban and James A. Moses
Sept. pp. 195-204

The Navy's Training Film Production
Program, Wilson R. Cronenwett and
William M. Timmons July pp. 49-57

GENERAL

A-C High-Intensity Arc Slide Projector,
Arthur J. Hatch Oct. pp. 335-337

X-ray Motion Picture Techniques Em-
ployed in Medical Diagnosis and Re-
search, S. A. Weinberg, J. S. Watson,
Jr., and G. H. Ramsey

Oct. pp. 300-308

Safety Requirements in Projection Rooms

and Television Studios, Samuel R. Todd

Sept. pp. 212-218

SMPTE Engineering Activities, Fred T.
Bowditch Sept. pp. 161-177

Canadian Standards Association, G. G.
Graham Aug. pp. 156-157

Un commercial phonoregistrator binaural
— Interlingua Translation of First Page
of "A Commercial Binaural Recorder,"
Alexander Gode Aug. p. 108

International Auxiliary Language for Mo-
tion Pictures, Mary Bray Aug. p. 107

HIGH-SPEED PHOTOGRAPHY
General

Optical Aids for High-Speed Photography,
David C. Gilkeson and A. Eugene
Turula Dec. pp. 498-502

Accuracy Limitations on High-Speed
Metric Photography, Amy E. Griffin
and Elmer E. Green Dec. pp. 485-492

The Economics of High-Speed Photog-
raphy, A. C. Keller Nov. pp. 365-368

HIGH-SPEED PHOTOGRAPHY
Applications

High-Speed Cine-Electrocardiography,
Joshua J. Fields, Louis Fields, Eleanor
Gerlach and Myron Prinzmetal

Dec. pp. 493-497

Motion Photography for Combustion Re-
search, Fred W. Bowditch

Dec. pp. 472-484

Transient Pressure Recording With a
High-Speed Interferometer Camera,
Willard E. Buck Nov. pp. 369-378

X-ray Motion Picture Techniques Em-
ployed in Medical Diagnosis and Re-
search, S. A. Weinberg, J. S. Watson
Jr., and G. H. Ramsey

Oct. pp. 300-308

Use of a Rotating-Drum Camera for
Recording Impact Loading Deforma-
tions, D. F. Muster and E. G. Volterra
July pp. 44-48

Cameras

A High-Speed Rotating-Mirror Frame
Camera, Berlyn Brixner

Dec. pp. 503-511

Transient Pressure Recording With a
High-Speed Interferometer Camera,
Willard E. Buck Nov. pp. 369-378

Use of a Rotating-Drum Camera for Re-
cording Impact Loading Deformations,
D. F. Muster and E. G. Volterra

July pp. 44-48

Lighting

Explosive Argon Flashlamp, C. H. Win-
ning and Harold E. Edgerton

Sept. pp. 178-183

LABORATORY PRACTICE

General

A Precision Color Temperature Meter for
Tungsten Illumination, G. H. Dawson,
D. E. Grant and H. F. Ott

Oct. pp. 309-312

Integrating-Type Color j«iDensitometer,
Frank P. Herrnfeld Sept. pp. 184-190

A Method of Direct-Positive Variable-
Density Recording With the Light
Valve, O. L. Dupy Aug. pp. 101-106

558

December 1952 Journal of the SMPTE Vol. 59

Nonsilver Photographic Processes, Thomas
T. Hill July pp. 58-66

Printing

American Standard Edge Numbering 16

mm Motion Picture Film, PH22.83-1952

Nov. p. 427

A Fast-Acting Exposure Control System for

Color Motion Picture Printing, John G.

Streiffert Nov. pp. 410-416

Densitometry of Silver Sulfide Sound

Tracks, Robert C. Lovick

Aug. pp. 89-93

Optimum Exposure of Sound Tracks on
Kodachrome Films, Robert C. Lovick

Aug. pp. 81-88

Dual-Purpose Optical Sound Prints, C. E.
Beachell and G. G. Graham

July pp. 1-10

LIGHTING

Motion Picture Studio Lighting Report,

John W. Boyle Nov. pp. 417-422

A-C High-Intensity Arc Slide Projector,

Arthur J. Hatch Oct. pp. 335-337

Explosive Argon Flashlamp, C. H. Winning

and Harold E. Edgerton

Sept. pp. 178-183
Modulated Air Blast for Reducing Film

Buckle, Willy Borberg Aug. pp. 94-100
Continuous Arc Projector Light Meter,

Harry P. Brueggemann July pp. 40-43

MOTOR-DRIVE SYSTEMS

Three-Phase Power From Single-Phase
Source, A. L. Holcomb July pp. 32-39

Automatic Torque Controller for Torque
Motors, Carl E. Kittle July pp. 28-31

NEW PRODUCTS

Portable Microphone Boom, National Cine

Equipment, Inc. Nov. p. 444

The Photovolt Densitometer, Photovolt

Corp. Nov. p. 444

Aluminized mirrors (for Schlieren), distr.

by J. A. Maurer, Inc. Oct. p. 364

Nema Movie Guide — 7952, published by

the National Electrical Manufacturers

Association Sept. p. 248

Electronic Humidity Controls, Bulletin

F-5173, Barber-Colman Co.

Sept. p. 248
Movie Sound 8, Movie Mite Corp.

Sept. p. 247

Hy-Arc Projection Lamp, RCA Victor Div.

Aug. p. 160

5000-w Featherlite, Century Lighting, Inc.

Aug. p. 160

Eidophor Theater Television, 20th Cen-
tury-Fox Film Corp. July p. 80

OBITUARIES

Brewster, Percy D.

Dec. p. 546

Levinson, Col. Nathan Oct. p. 360

Ross, Charles July p. 74

OPTICS

Optical Aids for High-Speed Photography,
David C. Gilkeson and A. Eugene
Turula Dec. pp. 498-502

'Optics Committee Report, Rudolf Kings-
lake Nov. p. 426

Proposed American Standard Aperture
Calibration of Motion Picture Lenses,
PH22.90 Oct. p. 338

X-ray Motion Picture Techniques Em-
ployed in Medical Diagnosis and Re-
search, S. A. Weinberg, J. S. Watson,
Jr., and G. H. Ramsey

Oct. pp. 300-308

Military-Type Lenses for 35mm Motion
Picture Cameras, Paul C. Foote and
R. E. Miesse Sept. pp. 219-232

Transmission Color in Camera Lenses,
Philip T. Scharf Sept. pp. 191-194

Follow-Focus Device and Camera Blimp
for 16mm Professional Camera, Lee R.
Richardson and William N. Gaisford

Aug. pp. 118-124

PHOTOMETRY (see also LIGHTING,
OPTICS and SCREEN BRIGHT-
NESS)

A Precision Color Temperature Meter for
Tungsten Illumination, G. H. Dawson,
D. E. Grant and H. F. Ott

Oct. pp. 309-312

Continuous Arc Projector Light Meter,
Harry P. Brueggemann July pp. 40-43

PRODUCTION

Cameo Film Production Technique,
Charles F. Hoban and James A. Moses
Sept. pp. 195-204

The Navy's Training Film Production
Program, Wilson R. Cronenwett and
William M. Timmons July pp. 49-57

PROJECTION

American Standard Reel Spindles for
16mm Motion Picture Projectors,
PH22.50-1952 Dec. p. 525

Some Geometrical Conditions for Depth
Effect in Motion Pictures, Eugene
Millet Dec. pp. 517-523

American Standard 16mm Motion Picture
Projection Reels (Correction), PH22.11-
1952 Sept. p. 233

Proposed American Standard 16mm Mo-
tion Picture Projector for Use with
Monochrome Television Film Chains
Operating on Full-Storage Basis (Fourth
Draft), PH22.91 Aug. p. 144

Modulated Air Blast for Reducing Film
Buckle, Willy Borberg Aug. pp. 94-1 00

Index to Subjects

559

SCREEN BRIGHTNESS

Screen Brightness Committee Report,
W. W. Lozier Dec. pp. 524-525

Continuous Arc Projector Light Meter,
Harry P. Brueggemann July pp. 40-43

SCREENS

New Direct- Vision Stereo-Projection
Screen, W. Wheeler Jennings and Pierre
Vanet July pp. 22-27

SENSITOMETRY (see also LABORA-
TORY PRACTICE)

Integrating-Type Color Densitometer,
Frank P. Herrnfeld Sept. pp. 184-190

A Method of Direct-Positive Variable-
Density Recording With the Light
Valve, O. L. Dupy Aug. pp. 101-106

Densitometry of Silver Sulfide Sound
Tracks, Robert C. Lovick

Aug. pp. 89-93

Optimum Exposure of Sound Tracks on
Kodachrome Films, Robert C. Lovick

Aug. pp. 81-88

Nonsilver Photographic Processes, Thomas
T. Hill July pp. 58-66

SOCIETY ACTIVITIES
General

Binding Volumes of the Journal

Dec. p. 556
Members and the Journal Overseas

Oct. p. 360
Journal on Microfilm Oct. p. 358

SMPTE Lapel Pins July p. 79

Awards and Citations

New Fellows of the Society Dec. p. 535
Journal Awards Dec. p. 536

Life Membership to William C. Kunzmann

Dec. p. 537

Progress Medal Award Dec. p. 538

Samuel L. Warner Memorial Award

Dec. p. 538
David Sarnoff Gold Medal Award

Dec. p. 539

Board of Governors Meetings

Sept. pp. 238-239 Dec. p. 540

Committee Reports

Screen Brightness Committee Report, W.
W. Lozier, Chairman Dec. pp. 524-525

Optics Committee Report, Rudolf Kings-
lake, Chairman Nov. p. 426

Film Dimensions Committee Report, E. K.
Carver, Chairman Nov. pp. 423-425

Motion Picture Studio Lighting Report,
John W. Boyle, Chairman

Nov. pp. 417-422

Constitution and Bylaws

Proposed Amendments to the Bylaws
(Notation of Approval, Dec. p. 540)

Aug. p. 153

Conventions

72d, Washington, D.C.

Announcements: Sept. p. 238; Aug. p.
154; July p. 67

Papers Presented : Dec. pp. 551-555

Report Nov. pp. 432-440

73d. Los Angeles

Announcement: Dec. p. 535

Engineering Activities (News and Brief
Reports)

Dec. pp. 542-543; Nov. pp. 440-441;
Sept. p. 240 and pp. 161-177; Aug. p.
155; July p. 69

Letters to the Editor

Stereoptics Ltd. Cameras for Telecinema
Film, L. Dudley and Raymond Spottis-
woode Sept. p. 241

Three-Dimensional Motion Picture
Nomenclature, L. Dudley and Robert
V. Bernier July pp. 70-74

New Members

Dec. p. 547 Sept. p. 245

Nov. p. 442 Aug. p. 158

Oct. p. 361 July p. 75

Officers and Governors of the Society

New Officers Dec. p. 541

Section and Subsection Activities

Organization of the Southwest Sub-
section Dec. p. 542

Organization of the San Francisco
Subsection Oct. pp. 356-357

Atlantic Coast Section Regional Meeting
at Atlanta Sept. p. 240

SOUND RECORDING

General

Comparison of Recording Processes (Re-
print), John G. Frayne

Oct. pp. 313-318

Three-Phase Power From Single-Phase
Source, A. L. Holcomb July pp. 32-39

Automatic Torque Controller for Torque
Motors, Carl E. Hittle July pp. 28-31

Magnetic

Dual Photomagnetic Intermediate Studio

Recording, John G. Frayne and John

P. Livadary Nov. pp. 388-397

A Building-Block Approach to Magnetic

Recording Equipment Design, Kurt

Singer and J. L. Pettus

Oct. pp. 319-334
A Commercial Binaural Recorder, Otto

C.Bixler Aug. pp. 109-117

560

December 1952 Journal of the SMPTE Vol. 59

Photographic

Dual Photomagnetic Intermediate Studio
Recording, John G. Frayne and John
P. Livadary Nov. pp. 388-397

Optimum Slit Height in Photographic
Sound Track, W. K. Grimwood and
J. R. Horak Nov. pp. 379-387

A Method of Direct-Positive Variable-
Density Recording With the Light Valve,
O. L. Dupy Aug. pp. 101-106

Densitometry of Silver Sulfide Sound
Tracks, Robert G. Lovick

Aug. pp. 89-93

Optimum Exposure of Sound Tracks on
Kodachrome Films, Robert G. Lovick

Aug. pp. 81-88

Dual-Purpose Optical Sound Prints, G. E.
Beachell and G. G. Graham

July pp. 1-10

SOUND REPRODUCTION

Acoustic Problems at the "Waldbuhne"
Open- Air Sound Theater in Berlin,
Hans Simon Dec. pp. 512-516

American Standard Scanning Beam Uni-
formity Test Film for 16mm Motion
Picture Sound Reproducers, Laboratory
Type (Correction), PH22.80-1950

Nov. p. 427

American Standard Scanning Beam Uni-
formity Test Film for 16mm Motion
Picture Sound Reproducers, Service
Type (Correction), PH22.81-1950

Nov. p. 427

SPECIAL EFFECTS

Some Geometrical Conditions for Depth

Effect in Motion Pictures, Eugene Millet

Dec. pp. 517-523

Animation for Individual Television Sta-
tions, Ernest F. Hiser Oct. pp. 293-299

Drawing in Three Dimensions for Anima-
tion and Stereoscopic Processes, Ernest
F. Hiser Oct. pp. 287-292

Basic Principles of the Three-Dimensional
Film, Raymond Spottiswoode, N. L.
Spottiswoode and Charles Smith (for
three errata, see Dec. p. 516)

Oct. pp. 249-286

STANDARDS AND RECOMMENDA-
TIONS: See the listing on p. 562 or
the specific subject heading.
International Standardization; Agenda
and Accomplishments of ISO/TC 36
Meeting, Fred T. Bowditch and Henry
Kogel Oct. pp. 349-355

SMPTE Engineering Activities, Fred T.

Bowditch Sept. pp. 161-177

Canadian Standards Association, G. G.

Graham Aug. 156-157

STEREOSCOPY

Some Geometrical Conditions for Depth
Effect in Motion Pictures, Eugene
Millet Dec. pp. 517-523

Drawing in Three Dimensions for Anima-
tion and Stereoscopic Processes, Ernest
F. Hiser Oct. pp. 287-292

Basic Principles of the Three-Dimensional
Film, Raymond Spottiswoode, N. L.
Spottiswoode and Charles Smith (for
three errata, see Dec. p. 516)

Oct. pp. 249-286

New Direct- Vision Stereo-Projection
Screen, W. Wheeler Jennings and
Pierre Vanet July pp. 22-27

Theory of Parallax Barriers, Sam H.
Kaplan July pp. 11-21

TELEVISION (see also LIGHTING and
THEATER TELEVISION)

Signal Corps Mobile Television System,
John S. Auld Dec. pp. 462-471

Television Facilities of the Canadian
Broadcasting Corp., J. E. Hayes

Nov. pp. 398-405

Safety Requirements in Projection Rooms

and Television Studios, Samuel R. Todd

Sept. pp. 212-218

Proposed American Standard 16mm Mo-
tion Picture Projector for Use With
Monochrome Television Film Chains
Operating on Full-Storage Basis (Fourth
Draft), PH22.91 Aug. p. 144

THEATER

Acoustic Problems at the "Waldbuhne"
Open-Air Sound Theater in Berlin
Hans Simon Dec. pp. 512-516

Safety Requirements in Projection Rooms
and Television Studios, Samuel R.
Todd Sept. pp. 212-218

Auditorium Specifically Designed for Tech-
nical Meetings, D. Max Beard and A. M.
Erickson Sept. pp. 205-21 1

THEATER TELEVISION

Theater Television Progress, Nathan L.
Halpern Aug. pp. 140-143

Instantaneous Theater Projection Tele-
vision System, Victor Trad and Ricardo
Muniz Aug. pp. 125-139

Index to Subjects

561

No.

American Standards -

Title

by numbers

Page, issue

PH22.93 Proposed, 35mm Motion Picture Short-Pitch Negative 527, Dec.

Film
PH22.12 Proposed, Dimensions for 16mm Single-Perforated 527, Dec.

Motion Picture Film (Rev. Z22. 12-1 947)
PH22.5 Proposed, Dimensions for 16mm Double-Perforated 527, Dec.

Motion Picture Film (Rev. Z22. 5-1947)

PH22. 50-1 952 Reel Spindles for 16mm Motion Picture Projectors 525, Dec.

PH22.83-1952 Edge Numbering 16mm Motion Picture Film 427, Nov.

PH22. 38-1 952 Raw Stock Gores for 16mm Motion Picture Film 427, Nov.

Z22. 33-1 941 Nomenclature for Electrical Filters (withdrawn) 427, Nov.

PH22. 80-1 950 Scanning Beam Uniformity Test Film for 16mm Mo- 427, Nov.

tion Picture Sound Reproducers, Laboratory Type

(Correction)
PH22.81-1950 Scanning Beam Uniformity Test Film for 16mm Mo- 427, Nov.

tion Picture Sound Reproducers, Service Type

(Correction)
PH22.90 Proposed, Aperture Calibration of Motion Picture 338, Oct.

Lenses

PH22.11-1952 16mm Motion Picture Projection Reels (Correction) 233, Sept.

PH22.91 Proposed, 16mm Motion Picture Projector for Use 144, Aug.

With Monochrome Television Film Chains Operat-
ing on Full-Storage Basis (Fourth Draft)

562

December 1952 Journal of the SMPTE Vol. 59

INDEX TO AUTHORS

July — December 1952 • Volume 59

Auld, John S., Signal Corps Mobile Television
System Dec. pp. 462-471

Beachell, C. E., and Graham, G. G., Dual-
Purpose Optical Sound Prints July pp. 1—10

Beard, D. Max, and Erickson, A. M., Audi-
torium Specifically Designed for Technical
Meetings Sept. pp. 205-211

Bixler, Otto C., A Commercial Binaural Re-
corder Aug. pp. 109-117

Borberg, Willy, Modulated Air Blast for
Reducing Film Buckle Aug. pp. 94-100

Bowditch, Fred T., Engineering Vice-President,
SMPTE Engineering Activities

Sept. pp. 161-177

Bowditch, Fred W., Motion Photography for
Combustion Research Dec. pp. 472-484

Boyle, John W., Chairman, Motion Picture
Studio Lighting Report Nov. pp. 417-422

Bray, Mary, International Auxiliary Language
for Motion Pictures Aug. p. 107

Brixner, Berlyn, A High-Speed Rotating-Mirror
Frame Camera Dec. pp. 503-511

Brueggemann, Harry P., Continuous Arc
Projector Light Meter July pp. 40-43

Buck, Willard E., Transient Pressure Recording
With a High-Speed Interferometer Camera

Nov. pp. 369-378

Carver, E. K., Chairman, Film Dimensions
Committee Report Nov. pp. 423-425

Collins, Norman, and Macnamara, T. C., The
Electronic Camera in Film-Making

Dec. pp. 445-461

Cronenwett, Wilson R., and Timmons, William
M., The Navy's Training Film Production
Program July pp. 49-57

Dawson, G. H., Grant, D. E., and Ott, H. F.,
A Precision Color Temperature Meter for
Tungsten Illumination Oct. pp. 309-312

Dupy, O. L., A Method of Direct-Positive
Variable-Density Recording With the Light
Valve Aug. pp. 101-106

Edgerton, Harold E., and Winning, C. H.,
Explosive Argon Flashlamp

Sept. pp. 178-183

Erickson, A. M., and Beard, D. Max, Audi-
torium Specifically Designed for Technical
Meetings Sept. pp. 205-211

Fields, Joshua J., Fields, Louis, Gerlach,
Eleanor, and Prinzmetal, Myron, High-Speed
Cine-Electrocardiography Dec. pp. 493-497

Foote, Paul C., and Miesse, R. E., Military-
Type Lenses for 35mm Motion Picture
Cameras Sept. pp. 219-232

Frayne, John G., Comparison of Recording
Processes (Reprint) Oct. pp. 313-318

Frayne, John G., and Livadary, John P., Dual
Photomagnetic Intermediate Studio Record-
ing Nov. pp. 388-397

Gaisford, William N., and Richardson, Lee R.,
Follow-Focus Device and Camera Blimp for
16mm Professional Camera

Aug. pp. 118-124

Gerlach, Eleanor, Prinzmetal, Myron, Fields,
Joshua J., and Fields, Louis, High-Speed
Cine-Electrocardiography

Dec. pp. 493-497

Gilkeson, David C., and Turula, A. Eugene,
Optical Aids for High-Speed Photography

Dec. pp. 498-502

Gode, Alexander, Un commercial phono-
registrator binaural — Interlingua Transla-
tion of First Page of "A Commercial Binaural
Recorder" Aug. p. 108

Graham, G. G., Canadian Standards Associa-
tion Aug. pp. 156-157

Graham, G. G., and Beachell, C. E., Dual-
Purpose Optical Sound Prints July pp. 1-10

Grant, D. E., Ott, H. F., and Dawson, G. H.,
A Precision Color Temperature Meter for
Tungsten Illumination Oct. pp. 309-312

Green, Elmer E., see Griffin, Amy E.

Griffin, Amy E., and Green, Elmer E., Accuracy
Limitations on High-Speed Metric Photog-
raphy Dec. pp. 485-492

Grimwood, W. K., and Horak, J. R., Optimum
Slit Height in Photographic Sound Track Re-
producers Nov. pp. 379-387

Halpern, Nathan L., Theater Television
Progress Aug. pp. 140-143

Hatch, Arthur J., A-C High-Intensity Arc Slide
Projector Oct. pp. 335-337

Hayes, J. E., Television Facilities of the
Canadian Broadcasting Corp.

Nov. pp. 398-405

Herrnfeld, Frank P., Integrating-Type Color
Densitometer Sept. pp. 184-190

Hill, Thomas T., Nonsilver Photographic
Processes July pp. 58-66

Hiser, Ernest F., Drawing in Three Dimensions
for Animation and Stereoscopic Processes

Oct. pp. 287-292

December 1952 Journal of the SMPTE Vol. 59

563

, Animation for Individual Television Sta-
tions Oct. pp. 293-299

Hittle, Carl E., Automatic Torque Controller
for Torque Motors July pp. 28-31

Hoban, Charles F., and Moses, James A.,
Cameo Film Production Technique

Sept. pp. 195-204

Holcomb, A. L., Three-Phase Power From
Single-Phase Source July pp. 32-39

Horak, J. R., and Grimwood, W. K., Optimum
Slit Height in Photographic Sound Track Re-
producers Nov. pp. 379-387

Jennings, W. Wheeler, and Vanet, Pierre,
New Direct-Vision Stereo-Projection Screen

July pp. 22-27

Kaplan, Sam H., Theory of Parallax Barriers

July pp. 11-21

Keller, A. C., The Economics of High-Speed
Photography Nov. pp. 365-368

Kingslake, Rudolf, Chairman, Optics Committee
Report Nov. p. 426

Livadary, John P., and Frayne, John G., Dual
Photomagnetic Intermediate Studio Re-
cording Nov. pp. 388-397

Lovick, Robert C., Optimum Exposure of Sound
Tracks on Kodachrome Films

Aug. pp. 81-88

— , Densitometry of Silver Sulfide Sound
Tracks Aug. pp. 89-93

Lozier, W. W., Chairman, Screen Brightness
Committee Report Dec. pp. 524-525

Macnamara, T. C., and Collins, Norman, The
Electronic Camera in Film-Making

Dec. pp. 445-461

Miesse, R. E., and Foote, Paul C., Military-Type
Lenses for 35mm Motion Picture Cameras

Sept. pp. 219-232

Millet, Eugene, Some Geometrical Conditions for
Depth Effect in Motion Pictures

Dec. pp. 517-523

Moses, James A., and Hoban, Charles F.,
Cameo Film Production Technique

Sept. pp. 195-204

Muniz, Ricardo, and Trad, Victor, Instan-
taneous Theater Projection Television System
Aug. pp. 125-139

Muster, D. F., and Volterra, E. G., Use of a
Rotating-Drum Camera for Recording Impact
Loading Deformations July pp. 44-48

Ott, H. F., Dawson, G. H., and Grant, D. E.,
A Precision Color Temperature Meter for
Tungsten Illumination

Oct. pp. 309-312

Pettus, J. L., and Singer, Kurt, A Building-
Block Approach to Magnetic Recording
Equipment Design Oct. pp. 319-334

Prinzmetal, Myron, Fields, Joshua J., Fields,
Louis, and Gerlach, Eleanor, High-Speed
Cine-EIectrocardiography Dec. pp. 493-497

Ramsey, G. H., Weinberg, S. A., and Watson,

J. S., Jr., X-ray Motion Picture Techniques

Employed in Medical Diagnosis and Research

Oct. pp. 300-308

Ray, Reid H., Use of Ansco Color Film in Com-
mercial Production Nov. pp. 406-409

Richardson, Lee R., and Gaisford, William N.,
Follow-Focus Device and Camera Blimp for
16mm Professional Camera

Aug. pp. 118-124

Scharf, Philip T., Transmission Color in Camera
Lenses Sept. pp. 191-194

Simon, Hans, Acoustic Problems at the "Wald-
biihne" Open-Air Sound Theater in Berlin

Dec. pp. 512-516

Singer, Kurt, and Pettus, J. L., A Building-
Block Approach to Magnetic Recording
Equipment Design Oct. pp. 319-334

Smith, Charles, see Spottiswoode, Raymond

Spottiswoode, Raymond, Spottiswoode, N. L.,
and Smith, Charles, Basic Principles of the
Three-Dimensional Film Oct. pp. 249-286
Errata Dec. p. 516

Streiffert, John G., A Fast-Acting Exposure
Control System for Color Motion Picture
Printing Nov. pp. 410-416

Timmons, William M., and Cronenwett,
Wilson R., The Navy's Training Film Pro-
duction Program July pp. 49-57

Todd, Samuel R., Safety Requirements in
Projection Rooms and Television Studios

Sept. pp. 212-218

Trad, Victor, and Muniz, Ricardo, Instan-
taneous Theater Projection Television System
Aug. pp. 125-139

Turula, A. Eugene, and Gilkeson, David C.,
Optical Aids for High-Speed Photography

Dec. pp. 498-502

Vanet, Pierre, and Jennings, W. Wheeler,
New Direct- Vision Stereo-Projection Screen
July pp. 22-27

Volterra, E. G., and Muster, D. F., Use of a
Rotating-Drum Camera for Recording Im-
pact Loading Deformations

July pp. 44-48

Watson, J. S., Jr., see Weinberg, S. A.

Weinberg, S. A., Watson, J. S., Jr., and
Ramsey, G. H., X-ray Motion Picture Tech-
niques Employed in Medical Diagnosis and
Research Oct. pp. 300-308

Winning, C. H., and Edgerton, Harold E.,
Explosive Argon Flashlamp

Sept. pp. 178-183

564

December 1952 Journal of the SMPTE Vol. 59

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